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

github_copilot_sdk/
tool.rs
