github_copilot_sdk/
tool.rs

1//! Typed tool definition framework.
2//!
3//! Provides the [`ToolHandler`](crate::tool::ToolHandler) trait for
4//! implementing tools as named types. Attach a handler to a
5//! [`Tool`](crate::types::Tool) via
6//! [`Tool::with_handler`](crate::types::Tool::with_handler), then install
7//! the resulting tools on a session via
8//! [`SessionConfig::with_tools`](crate::types::SessionConfig::with_tools).
9//! The SDK builds an internal name-keyed registry from the handlers and
10//! dispatches to the matching handler when the CLI broadcasts
11//! `external_tool.requested`.
12//!
13//! Enable the `derive` feature for `schema_for`, which generates JSON
14//! Schema from Rust types via `schemars`.
15
16use async_trait::async_trait;
17use indexmap::IndexMap;
18/// Re-export of [`schemars::JsonSchema`] for deriving tool parameter schemas.
19#[cfg(feature = "derive")]
20pub use schemars::JsonSchema;
21
22use crate::Error;
23#[cfg(any(feature = "derive", test))]
24use crate::types::Tool;
25use crate::types::{ToolBinaryResult, ToolInvocation, ToolResult, ToolResultExpanded};
26
27/// Generate a JSON Schema [`Value`](serde_json::Value) from a Rust type.
28///
29/// Strips `$schema` and `title` root-level metadata so the output is ready
30/// to use as [`Tool::parameters`].
31///
32/// # Example
33///
34/// ```rust
35/// use github_copilot_sdk::tool::{schema_for, JsonSchema};
36///
37/// #[derive(JsonSchema)]
38/// struct Params {
39///     /// City name
40///     city: String,
41/// }
42///
43/// let schema = schema_for::<Params>();
44/// assert_eq!(schema["type"], "object");
45/// assert!(schema["properties"]["city"].is_object());
46/// ```
47#[cfg(feature = "derive")]
48pub fn schema_for<T: schemars::JsonSchema>() -> serde_json::Value {
49    let schema = schemars::schema_for!(T);
50    let mut value = serde_json::to_value(schema).expect("JSON Schema serialization cannot fail");
51    if let Some(obj) = value.as_object_mut() {
52        obj.remove("$schema");
53        obj.remove("title");
54    }
55    value
56}
57
58/// Convert a JSON Schema [`Value`](serde_json::Value) into the
59/// [`Tool::parameters`](crate::types::Tool::parameters) map shape
60/// expected by the protocol.
61///
62/// Panics if the input is not a JSON object — tool parameter schemas
63/// are always top-level objects (`{"type": "object", ...}`). Pair with
64/// `schema_for` (available with the `derive` feature) or a
65/// `serde_json::json!(...)` literal.
66///
67/// Use [`try_tool_parameters`] when the schema comes from dynamic input and
68/// should return a recoverable error instead of panicking.
69///
70/// # Example
71///
72/// ```rust
73/// use github_copilot_sdk::tool::tool_parameters;
74/// use github_copilot_sdk::Tool;
75///
76/// let mut tool = Tool::default();
77/// tool.name = "ping".to_string();
78/// tool.description = "ping the server".to_string();
79/// tool.parameters = tool_parameters(serde_json::json!({"type": "object"}));
80/// # let _ = tool;
81/// ```
82pub fn tool_parameters(schema: serde_json::Value) -> IndexMap<String, serde_json::Value> {
83    try_tool_parameters(schema).expect("tool parameter schema must be a JSON object")
84}
85
86/// Fallible variant of [`tool_parameters`] for callers handling dynamic schema input.
87pub fn try_tool_parameters(
88    schema: serde_json::Value,
89) -> Result<IndexMap<String, serde_json::Value>, serde_json::Error> {
90    serde_json::from_value(schema)
91}
92
93/// Convert an MCP `CallToolResult` JSON value into a Copilot tool result.
94///
95/// Returns `None` when the value is not shaped like a `CallToolResult`.
96pub fn convert_mcp_call_tool_result(value: &serde_json::Value) -> Option<ToolResult> {
97    let content = value.get("content")?.as_array()?;
98    let mut text_parts = Vec::new();
99    let mut binary_results = Vec::new();
100
101    for block in content {
102        match block.get("type").and_then(serde_json::Value::as_str) {
103            Some("text") => {
104                if let Some(text) = block.get("text").and_then(serde_json::Value::as_str) {
105                    text_parts.push(text.to_string());
106                }
107            }
108            Some("image") => {
109                let data = block
110                    .get("data")
111                    .and_then(serde_json::Value::as_str)
112                    .filter(|s| !s.is_empty());
113                let mime_type = block
114                    .get("mimeType")
115                    .and_then(serde_json::Value::as_str)
116                    .filter(|s| !s.is_empty());
117                if let (Some(data), Some(mime_type)) = (data, mime_type) {
118                    binary_results.push(ToolBinaryResult {
119                        data: data.to_string(),
120                        mime_type: mime_type.to_string(),
121                        r#type: "image".to_string(),
122                        description: None,
123                    });
124                }
125            }
126            Some("resource") => {
127                let Some(resource) = block.get("resource").and_then(serde_json::Value::as_object)
128                else {
129                    continue;
130                };
131                if let Some(text) = resource
132                    .get("text")
133                    .and_then(serde_json::Value::as_str)
134                    .filter(|s| !s.is_empty())
135                {
136                    text_parts.push(text.to_string());
137                }
138                if let Some(blob) = resource
139                    .get("blob")
140                    .and_then(serde_json::Value::as_str)
141                    .filter(|s| !s.is_empty())
142                {
143                    let mime_type = resource
144                        .get("mimeType")
145                        .and_then(serde_json::Value::as_str)
146                        .filter(|s| !s.is_empty())
147                        .unwrap_or("application/octet-stream");
148                    let description = resource
149                        .get("uri")
150                        .and_then(serde_json::Value::as_str)
151                        .filter(|s| !s.is_empty())
152                        .map(ToString::to_string);
153                    binary_results.push(ToolBinaryResult {
154                        data: blob.to_string(),
155                        mime_type: mime_type.to_string(),
156                        r#type: "resource".to_string(),
157                        description,
158                    });
159                }
160            }
161            _ => {}
162        }
163    }
164
165    Some(ToolResult::Expanded(ToolResultExpanded {
166        text_result_for_llm: text_parts.join("\n"),
167        result_type: if value.get("isError").and_then(serde_json::Value::as_bool) == Some(true) {
168            "failure".to_string()
169        } else {
170            "success".to_string()
171        },
172        binary_results_for_llm: (!binary_results.is_empty()).then_some(binary_results),
173        session_log: None,
174        error: None,
175        tool_telemetry: None,
176        tool_references: None,
177    }))
178}
179
180/// A client-defined tool's runtime implementation.
181///
182/// Implement this trait when you want to bind a Rust function to a tool
183/// name and have the SDK dispatch matching `external_tool.requested`
184/// broadcasts to it. Attach the impl to a [`Tool`](crate::types::Tool)
185/// via [`Tool::with_handler`](crate::types::Tool::with_handler).
186///
187/// Named handler types (e.g. `struct MyTool;`) are visible in stack
188/// traces and navigable via "go to definition", which is preferable to
189/// closure-based alternatives for non-trivial tools. For trivial tools,
190/// the `define_tool` helper function (available with the `derive`
191/// feature) wraps a free `async fn` or closure into a [`Tool`](crate::types::Tool) with
192/// the handler already attached.
193///
194/// # Example
195///
196/// ```rust,ignore
197/// use github_copilot_sdk::tool::{schema_for, JsonSchema, ToolHandler};
198/// use github_copilot_sdk::types::{Tool, ToolInvocation};
199/// use github_copilot_sdk::{Error, ToolResult};
200/// use serde::Deserialize;
201/// use async_trait::async_trait;
202/// use std::sync::Arc;
203///
204/// #[derive(Deserialize, JsonSchema)]
205/// struct GetWeatherParams {
206///     /// City name
207///     city: String,
208/// }
209///
210/// struct GetWeather;
211///
212/// #[async_trait]
213/// impl ToolHandler for GetWeather {
214///     async fn call(&self, inv: ToolInvocation) -> Result<ToolResult, Error> {
215///         let params: GetWeatherParams = serde_json::from_value(inv.arguments)?;
216///         Ok(ToolResult::Text(format!("Weather in {}: sunny", params.city)))
217///     }
218/// }
219///
220/// // Build the Tool declaration with the handler attached:
221/// let tool = Tool::new("get_weather")
222///     .with_description("Get weather for a city")
223///     .with_parameters(schema_for::<GetWeatherParams>())
224///     .with_handler(Arc::new(GetWeather));
225/// ```
226#[async_trait]
227pub trait ToolHandler: Send + Sync + 'static {
228    /// Handle a tool invocation from the agent.
229    async fn call(&self, invocation: ToolInvocation) -> Result<ToolResult, Error>;
230}
231
232/// Define a [`Tool`] from an async function (or closure) that takes a typed,
233/// `JsonSchema`-derived parameter struct.
234///
235/// The returned [`Tool`] carries an attached handler ready to install on a
236/// session via [`SessionConfig::with_tools`](crate::types::SessionConfig::with_tools).
237/// JSON Schema for the parameter type is generated via [`schema_for`] at
238/// construction time.
239///
240/// The handler bound (`Fn(ToolInvocation, P) -> Fut + Send + Sync + 'static`)
241/// accepts both bare `async fn` items and closures — the same shape as
242/// [`tower::service_fn`][tower-service-fn] and
243/// [`hyper::service::service_fn`][hyper-service-fn]. Prefer a free `async fn`
244/// for non-trivial tools so it shows up in stack traces by name.
245///
246/// The closure receives the full [`ToolInvocation`] alongside the deserialized
247/// parameters so handlers can use `inv.session_id`, `inv.tool_call_id`, or
248/// other invocation metadata. Handlers that don't need that metadata can
249/// destructure with `|_inv, params|`.
250///
251/// # Example
252///
253/// ```rust,no_run
254/// use github_copilot_sdk::tool::{define_tool, JsonSchema};
255/// use github_copilot_sdk::types::ToolInvocation;
256/// use github_copilot_sdk::{Error, ToolResult};
257/// use serde::Deserialize;
258///
259/// #[derive(Deserialize, JsonSchema)]
260/// struct GetWeatherParams {
261///     /// City name
262///     city: String,
263/// }
264///
265/// async fn get_weather(
266///     inv: ToolInvocation,
267///     params: GetWeatherParams,
268/// ) -> Result<ToolResult, Error> {
269///     let _ = inv.session_id;
270///     Ok(ToolResult::Text(format!("Sunny in {}", params.city)))
271/// }
272///
273/// // Pass a free async fn — preferred for non-trivial tools.
274/// let tool = define_tool("get_weather", "Get weather for a city", get_weather);
275///
276/// // ...or an inline closure when the body is trivial.
277/// let tool = define_tool(
278///     "echo",
279///     "Echo the input",
280///     |_inv, params: GetWeatherParams| async move {
281///         Ok(ToolResult::Text(params.city))
282///     },
283/// );
284/// # let _ = tool;
285/// ```
286///
287/// [tower-service-fn]: https://docs.rs/tower/latest/tower/fn.service_fn.html
288/// [hyper-service-fn]: https://docs.rs/hyper/latest/hyper/service/fn.service_fn.html
289#[cfg(feature = "derive")]
290pub fn define_tool<P, F, Fut>(
291    name: impl Into<String>,
292    description: impl Into<String>,
293    handler: F,
294) -> Tool
295where
296    P: schemars::JsonSchema + serde::de::DeserializeOwned + Send + 'static,
297    F: Fn(ToolInvocation, P) -> Fut + Send + Sync + 'static,
298    Fut: std::future::Future<Output = Result<ToolResult, Error>> + Send + 'static,
299{
300    struct FnHandler<P, F> {
301        handler: F,
302        _marker: std::marker::PhantomData<fn(P)>,
303    }
304
305    #[async_trait]
306    impl<P, F, Fut> ToolHandler for FnHandler<P, F>
307    where
308        P: schemars::JsonSchema + serde::de::DeserializeOwned + Send + 'static,
309        F: Fn(ToolInvocation, P) -> Fut + Send + Sync + 'static,
310        Fut: std::future::Future<Output = Result<ToolResult, Error>> + Send + 'static,
311    {
312        async fn call(&self, mut invocation: ToolInvocation) -> Result<ToolResult, Error> {
313            let arguments = std::mem::take(&mut invocation.arguments);
314            let params: P = serde_json::from_value(arguments)?;
315            (self.handler)(invocation, params).await
316        }
317    }
318
319    Tool {
320        name: name.into(),
321        description: description.into(),
322        parameters: tool_parameters(schema_for::<P>()),
323        ..Default::default()
324    }
325    .with_handler(std::sync::Arc::new(FnHandler {
326        handler,
327        _marker: std::marker::PhantomData,
328    }))
329}
330
331/// Define a declaration-only [`Tool`] with a JSON Schema derived from `P`.
332///
333/// Equivalent to [`define_tool`] but produces a [`Tool`] with no attached
334/// handler — useful when another connected client services this tool, or
335/// when you only need to advertise the schema for capability negotiation.
336///
337/// # Example
338///
339/// ```rust,no_run
340/// use github_copilot_sdk::tool::{define_tool_declaration, JsonSchema};
341/// use serde::Deserialize;
342///
343/// #[derive(Deserialize, JsonSchema)]
344/// struct Params { query: String }
345///
346/// let declared = define_tool_declaration::<Params>(
347///     "legacy_thing",
348///     "Handled by another connected client",
349/// );
350/// # let _ = declared;
351/// ```
352#[cfg(feature = "derive")]
353pub fn define_tool_declaration<P>(name: impl Into<String>, description: impl Into<String>) -> Tool
354where
355    P: schemars::JsonSchema,
356{
357    Tool {
358        name: name.into(),
359        description: description.into(),
360        parameters: tool_parameters(schema_for::<P>()),
361        ..Default::default()
362    }
363}
364
365#[cfg(test)]
366mod tests {
367    use super::*;
368    use crate::types::SessionId;
369
370    struct EchoTool;
371
372    fn echo_tool() -> Tool {
373        Tool {
374            name: "echo".to_string(),
375            description: "Echo the input".to_string(),
376            parameters: tool_parameters(serde_json::json!({"type": "object"})),
377            ..Default::default()
378        }
379        .with_handler(std::sync::Arc::new(EchoTool))
380    }
381
382    #[async_trait]
383    impl ToolHandler for EchoTool {
384        async fn call(&self, inv: ToolInvocation) -> Result<ToolResult, Error> {
385            Ok(ToolResult::Text(inv.arguments.to_string()))
386        }
387    }
388
389    #[test]
390    fn tool_handler_returns_tool_definition() {
391        let def = echo_tool();
392        assert_eq!(def.name, "echo");
393        assert_eq!(def.description, "Echo the input");
394        assert!(def.parameters.contains_key("type"));
395        assert!(def.handler.is_some());
396    }
397
398    #[test]
399    fn try_tool_parameters_rejects_non_object_schema() {
400        let err = try_tool_parameters(serde_json::json!(["not", "an", "object"]))
401            .expect_err("non-object schemas should be rejected");
402
403        assert!(err.is_data());
404    }
405
406    #[test]
407    fn tool_parameters_serialize_in_deterministic_order() {
408        // Regression: `Tool.parameters` was a `HashMap`, whose per-instance
409        // random iteration order made the serialized top-level schema keys
410        // differ between constructions (and between sessions), busting the
411        // model provider's prompt cache. `IndexMap` keeps the order stable.
412        let schema = serde_json::json!({
413            "type": "object",
414            "properties": {
415                "url": { "type": "string" },
416                "count": { "type": "integer" }
417            },
418            "required": ["url"],
419            "additionalProperties": false
420        });
421
422        let build = || Tool {
423            name: "fetch".to_string(),
424            parameters: tool_parameters(schema.clone()),
425            ..Default::default()
426        };
427
428        let expected = serde_json::to_string(&build()).expect("serialize tool");
429        for _ in 0..64 {
430            let actual = serde_json::to_string(&build()).expect("serialize tool");
431            assert_eq!(actual, expected);
432        }
433
434        // Pin the exact top-level key order so a regression to any
435        // order-randomizing container is caught, not just internal drift.
436        let tool = build();
437        let keys: Vec<&str> = tool.parameters.keys().map(String::as_str).collect();
438        assert_eq!(
439            keys,
440            ["additionalProperties", "properties", "required", "type"]
441        );
442    }
443
444    #[test]
445    fn convert_mcp_call_tool_result_collects_text_and_binary_content() {
446        let result = convert_mcp_call_tool_result(&serde_json::json!({
447            "isError": true,
448            "content": [
449                { "type": "text", "text": "hello" },
450                { "type": "image", "data": "aW1n", "mimeType": "image/png" },
451                {
452                    "type": "resource",
453                    "resource": {
454                        "uri": "file:///tmp/data.bin",
455                        "blob": "Ymlu",
456                        "mimeType": "application/octet-stream",
457                        "text": "resource text"
458                    }
459                }
460            ]
461        }))
462        .expect("valid CallToolResult should convert");
463
464        let ToolResult::Expanded(expanded) = result else {
465            panic!("expected expanded tool result");
466        };
467
468        assert_eq!(expanded.text_result_for_llm, "hello\nresource text");
469        assert_eq!(expanded.result_type, "failure");
470        let binary_results = expanded
471            .binary_results_for_llm
472            .expect("binary results should be captured");
473        assert_eq!(binary_results.len(), 2);
474        assert_eq!(binary_results[0].r#type, "image");
475        assert_eq!(binary_results[0].data, "aW1n");
476        assert_eq!(binary_results[0].mime_type, "image/png");
477        assert_eq!(
478            binary_results[1].description.as_deref(),
479            Some("file:///tmp/data.bin")
480        );
481    }
482
483    #[test]
484    fn convert_mcp_call_tool_result_converts_image_content() {
485        let result = convert_mcp_call_tool_result(&serde_json::json!({
486            "content": [
487                { "type": "image", "data": "aW1hZ2U=", "mimeType": "image/jpeg" }
488            ]
489        }))
490        .expect("valid CallToolResult should convert");
491
492        let ToolResult::Expanded(expanded) = result else {
493            panic!("expected expanded tool result");
494        };
495
496        assert_eq!(expanded.text_result_for_llm, "");
497        assert_eq!(expanded.result_type, "success");
498        let binary_results = expanded
499            .binary_results_for_llm
500            .expect("image result should be captured");
501        assert_eq!(binary_results.len(), 1);
502        assert_eq!(binary_results[0].data, "aW1hZ2U=");
503        assert_eq!(binary_results[0].mime_type, "image/jpeg");
504        assert_eq!(binary_results[0].r#type, "image");
505        assert!(binary_results[0].description.is_none());
506    }
507
508    #[test]
509    fn convert_mcp_call_tool_result_converts_resource_blob_content() {
510        let result = convert_mcp_call_tool_result(&serde_json::json!({
511            "content": [
512                {
513                    "type": "resource",
514                    "resource": {
515                        "uri": "file:///tmp/report.pdf",
516                        "blob": "cGRm",
517                        "mimeType": "application/pdf"
518                    }
519                }
520            ]
521        }))
522        .expect("valid CallToolResult should convert");
523
524        let ToolResult::Expanded(expanded) = result else {
525            panic!("expected expanded tool result");
526        };
527
528        let binary_results = expanded
529            .binary_results_for_llm
530            .expect("resource result should be captured");
531        assert_eq!(binary_results.len(), 1);
532        assert_eq!(binary_results[0].data, "cGRm");
533        assert_eq!(binary_results[0].mime_type, "application/pdf");
534        assert_eq!(binary_results[0].r#type, "resource");
535        assert_eq!(
536            binary_results[0].description.as_deref(),
537            Some("file:///tmp/report.pdf")
538        );
539    }
540
541    #[test]
542    fn convert_mcp_call_tool_result_defaults_resource_blob_mime_type() {
543        let result = convert_mcp_call_tool_result(&serde_json::json!({
544            "content": [
545                {
546                    "type": "resource",
547                    "resource": {
548                        "uri": "file:///tmp/data.bin",
549                        "blob": "Ymlu"
550                    }
551                },
552                {
553                    "type": "resource",
554                    "resource": {
555                        "blob": "YmluMg==",
556                        "mimeType": ""
557                    }
558                }
559            ]
560        }))
561        .expect("valid CallToolResult should convert");
562
563        let ToolResult::Expanded(expanded) = result else {
564            panic!("expected expanded tool result");
565        };
566
567        let binary_results = expanded
568            .binary_results_for_llm
569            .expect("resource blobs should be captured");
570        assert_eq!(binary_results.len(), 2);
571        assert_eq!(binary_results[0].mime_type, "application/octet-stream");
572        assert_eq!(binary_results[1].mime_type, "application/octet-stream");
573    }
574
575    #[test]
576    fn convert_mcp_call_tool_result_omits_binary_results_without_binary_content() {
577        let result = convert_mcp_call_tool_result(&serde_json::json!({
578            "content": [
579                { "type": "text", "text": "hello" },
580                {
581                    "type": "resource",
582                    "resource": {
583                        "uri": "file:///tmp/readme.md",
584                        "text": "resource text"
585                    }
586                }
587            ]
588        }))
589        .expect("valid CallToolResult should convert");
590
591        let ToolResult::Expanded(expanded) = result else {
592            panic!("expected expanded tool result");
593        };
594
595        assert_eq!(expanded.text_result_for_llm, "hello\nresource text");
596        assert!(expanded.binary_results_for_llm.is_none());
597    }
598
599    #[tokio::test]
600    async fn tool_handler_call_returns_result() {
601        let tool = EchoTool;
602        let inv = ToolInvocation {
603            session_id: SessionId::from("s1"),
604            tool_call_id: "tc1".to_string(),
605            tool_name: "echo".to_string(),
606            arguments: serde_json::json!({"msg": "hello"}),
607            available_tools: None,
608            traceparent: None,
609            tracestate: None,
610        };
611
612        let result = tool.call(inv).await.unwrap();
613        match result {
614            ToolResult::Text(s) => assert!(s.contains("hello")),
615            _ => panic!("expected Text result"),
616        }
617    }
618
619    #[cfg(feature = "derive")]
620    #[tokio::test]
621    async fn define_tool_builds_schema_and_dispatches() {
622        use serde::Deserialize;
623
624        #[derive(Deserialize, schemars::JsonSchema)]
625        struct Params {
626            city: String,
627        }
628
629        let tool = define_tool(
630            "weather",
631            "Get the weather for a city",
632            |_inv, params: Params| async move {
633                Ok(ToolResult::Text(format!("sunny in {}", params.city)))
634            },
635        );
636
637        assert_eq!(tool.name, "weather");
638        assert_eq!(tool.description, "Get the weather for a city");
639        assert_eq!(tool.parameters["type"], "object");
640        assert!(tool.parameters["properties"]["city"].is_object());
641        let handler = tool.handler.as_ref().expect("define_tool attaches handler");
642
643        let inv = ToolInvocation {
644            session_id: SessionId::from("s1"),
645            tool_call_id: "tc1".to_string(),
646            tool_name: "weather".to_string(),
647            arguments: serde_json::json!({"city": "Seattle"}),
648            available_tools: None,
649            traceparent: None,
650            tracestate: None,
651        };
652        match handler.call(inv).await.unwrap() {
653            ToolResult::Text(s) => assert_eq!(s, "sunny in Seattle"),
654            _ => panic!("expected Text result"),
655        }
656    }
657
658    // Tests requiring `schemars` (the `derive` feature).
659    #[cfg(feature = "derive")]
660    mod derive_tests {
661        use serde::Deserialize;
662
663        use super::super::*;
664        use crate::{ErrorKind, SessionId};
665
666        #[derive(Deserialize, schemars::JsonSchema)]
667        struct GetWeatherParams {
668            /// City name to get weather for.
669            city: String,
670            /// Temperature unit (celsius or fahrenheit).
671            unit: Option<String>,
672        }
673
674        #[test]
675        fn schema_for_generates_clean_schema() {
676            let schema = schema_for::<GetWeatherParams>();
677            assert_eq!(schema["type"], "object");
678            assert!(schema["properties"]["city"].is_object());
679            assert!(schema["properties"]["unit"].is_object());
680            // city is required (non-Option), unit is not
681            let required = schema["required"].as_array().unwrap();
682            assert!(required.contains(&serde_json::json!("city")));
683            assert!(!required.contains(&serde_json::json!("unit")));
684            // Root-level metadata stripped
685            assert!(schema.get("$schema").is_none());
686            assert!(schema.get("title").is_none());
687        }
688
689        struct GetWeatherTool;
690
691        fn get_weather_tool() -> Tool {
692            Tool {
693                name: "get_weather".to_string(),
694                description: "Get weather for a city".to_string(),
695                parameters: tool_parameters(schema_for::<GetWeatherParams>()),
696                ..Default::default()
697            }
698            .with_handler(std::sync::Arc::new(GetWeatherTool))
699        }
700
701        #[async_trait]
702        impl ToolHandler for GetWeatherTool {
703            async fn call(&self, inv: ToolInvocation) -> Result<ToolResult, Error> {
704                let params: GetWeatherParams = serde_json::from_value(inv.arguments)?;
705                Ok(ToolResult::Text(format!(
706                    "{} {}",
707                    params.city,
708                    params.unit.unwrap_or_default()
709                )))
710            }
711        }
712
713        #[test]
714        fn tool_handler_with_schema_for() {
715            let def = get_weather_tool();
716            assert_eq!(def.name, "get_weather");
717            let schema = serde_json::to_value(&def.parameters).expect("serialize tool parameters");
718            assert_eq!(schema["type"], "object");
719            assert!(schema["properties"]["city"].is_object());
720            assert!(def.handler.is_some());
721        }
722
723        #[tokio::test]
724        async fn tool_handler_deserializes_typed_params() {
725            let tool = GetWeatherTool;
726            let inv = ToolInvocation {
727                session_id: SessionId::from("s1"),
728                tool_call_id: "tc1".to_string(),
729                tool_name: "get_weather".to_string(),
730                arguments: serde_json::json!({"city": "Seattle", "unit": "celsius"}),
731                available_tools: None,
732                traceparent: None,
733                tracestate: None,
734            };
735
736            let result = tool.call(inv).await.unwrap();
737            match result {
738                ToolResult::Text(s) => assert_eq!(s, "Seattle celsius"),
739                _ => panic!("expected Text result"),
740            }
741        }
742
743        #[tokio::test]
744        async fn tool_handler_returns_error_on_bad_params() {
745            let tool = GetWeatherTool;
746            let inv = ToolInvocation {
747                session_id: SessionId::from("s1"),
748                tool_call_id: "tc1".to_string(),
749                tool_name: "get_weather".to_string(),
750                arguments: serde_json::json!({"wrong_field": 42}),
751                available_tools: None,
752                traceparent: None,
753                tracestate: None,
754            };
755
756            let err = tool.call(inv).await.unwrap_err();
757            assert!(matches!(err.kind(), ErrorKind::Json));
758        }
759
760        #[tokio::test]
761        async fn schema_for_derived_tool_round_trips_through_call() {
762            let tool = GetWeatherTool;
763
764            // Calling the tool with matching arguments returns the
765            // expected typed result. (Per-name dispatch is the SDK's
766            // concern; here we exercise just the handler contract.)
767            let result = tool
768                .call(ToolInvocation {
769                    session_id: SessionId::from("s1"),
770                    tool_call_id: "tc1".to_string(),
771                    tool_name: "get_weather".to_string(),
772                    arguments: serde_json::json!({"city": "Portland"}),
773                    available_tools: None,
774                    traceparent: None,
775                    tracestate: None,
776                })
777                .await
778                .expect("ToolHandler::call should succeed for matching args");
779            match result {
780                ToolResult::Text(s) => assert!(s.contains("Portland")),
781                _ => panic!("expected ToolResult::Text"),
782            }
783        }
784    }
785}
github_copilot_sdk/tool.rs

github_copilot_sdk/
tool.rs
