rig/
tool.rs

1//! Module defining tool related structs and traits.
2//!
3//! The [Tool] trait defines a simple interface for creating tools that can be used
4//! by [Agents](crate::agent::Agent).
5//!
6//! The [ToolEmbedding] trait extends the [Tool] trait to allow for tools that can be
7//! stored in a vector store and RAGged.
8//!
9//! The [ToolSet] struct is a collection of tools that can be used by an [Agent](crate::agent::Agent)
10//! and optionally RAGged.
11
12use std::{collections::HashMap, pin::Pin};
13
14use futures::Future;
15use serde::{Deserialize, Serialize};
16
17use crate::{
18    completion::{self, ToolDefinition},
19    embeddings::{embed::EmbedError, tool::ToolSchema},
20};
21
22#[derive(Debug, thiserror::Error)]
23pub enum ToolError {
24    /// Error returned by the tool
25    #[error("ToolCallError: {0}")]
26    ToolCallError(#[from] Box<dyn std::error::Error + Send + Sync>),
27
28    #[error("JsonError: {0}")]
29    JsonError(#[from] serde_json::Error),
30}
31
32/// Trait that represents a simple LLM tool
33///
34/// # Example
35/// ```
36/// use rig::{
37///     completion::ToolDefinition,
38///     tool::{ToolSet, Tool},
39/// };
40///
41/// #[derive(serde::Deserialize)]
42/// struct AddArgs {
43///     x: i32,
44///     y: i32,
45/// }
46///
47/// #[derive(Debug, thiserror::Error)]
48/// #[error("Math error")]
49/// struct MathError;
50///
51/// #[derive(serde::Deserialize, serde::Serialize)]
52/// struct Adder;
53///
54/// impl Tool for Adder {
55///     const NAME: &'static str = "add";
56///
57///     type Error = MathError;
58///     type Args = AddArgs;
59///     type Output = i32;
60///
61///     async fn definition(&self, _prompt: String) -> ToolDefinition {
62///         ToolDefinition {
63///             name: "add".to_string(),
64///             description: "Add x and y together".to_string(),
65///             parameters: serde_json::json!({
66///                 "type": "object",
67///                 "properties": {
68///                     "x": {
69///                         "type": "number",
70///                         "description": "The first number to add"
71///                     },
72///                     "y": {
73///                         "type": "number",
74///                         "description": "The second number to add"
75///                     }
76///                 }
77///             })
78///         }
79///     }
80///
81///     async fn call(&self, args: Self::Args) -> Result<Self::Output, Self::Error> {
82///         let result = args.x + args.y;
83///         Ok(result)
84///     }
85/// }
86/// ```
87pub trait Tool: Sized + Send + Sync {
88    /// The name of the tool. This name should be unique.
89    const NAME: &'static str;
90
91    /// The error type of the tool.
92    type Error: std::error::Error + Send + Sync + 'static;
93    /// The arguments type of the tool.
94    type Args: for<'a> Deserialize<'a> + Send + Sync;
95    /// The output type of the tool.
96    type Output: Serialize;
97
98    /// A method returning the name of the tool.
99    fn name(&self) -> String {
100        Self::NAME.to_string()
101    }
102
103    /// A method returning the tool definition. The user prompt can be used to
104    /// tailor the definition to the specific use case.
105    fn definition(&self, _prompt: String) -> impl Future<Output = ToolDefinition> + Send + Sync;
106
107    /// The tool execution method.
108    /// Both the arguments and return value are a String since these values are meant to
109    /// be the output and input of LLM models (respectively)
110    fn call(
111        &self,
112        args: Self::Args,
113    ) -> impl Future<Output = Result<Self::Output, Self::Error>> + Send;
114}
115
116/// Trait that represents an LLM tool that can be stored in a vector store and RAGged
117pub trait ToolEmbedding: Tool {
118    type InitError: std::error::Error + Send + Sync + 'static;
119
120    /// Type of the tool' context. This context will be saved and loaded from the
121    /// vector store when ragging the tool.
122    /// This context can be used to store the tool's static configuration and local
123    /// context.
124    type Context: for<'a> Deserialize<'a> + Serialize;
125
126    /// Type of the tool's state. This state will be passed to the tool when initializing it.
127    /// This state can be used to pass runtime arguments to the tool such as clients,
128    /// API keys and other configuration.
129    type State: Send;
130
131    /// A method returning the documents that will be used as embeddings for the tool.
132    /// This allows for a tool to be retrieved from multiple embedding "directions".
133    /// If the tool will not be RAGged, this method should return an empty vector.
134    fn embedding_docs(&self) -> Vec<String>;
135
136    /// A method returning the context of the tool.
137    fn context(&self) -> Self::Context;
138
139    /// A method to initialize the tool from the context, and a state.
140    fn init(state: Self::State, context: Self::Context) -> Result<Self, Self::InitError>;
141}
142
143/// Wrapper trait to allow for dynamic dispatch of simple tools
144pub trait ToolDyn: Send + Sync {
145    fn name(&self) -> String;
146
147    fn definition(
148        &self,
149        prompt: String,
150    ) -> Pin<Box<dyn Future<Output = ToolDefinition> + Send + Sync + '_>>;
151
152    fn call(
153        &self,
154        args: String,
155    ) -> Pin<Box<dyn Future<Output = Result<String, ToolError>> + Send + '_>>;
156}
157
158impl<T: Tool> ToolDyn for T {
159    fn name(&self) -> String {
160        self.name()
161    }
162
163    fn definition(
164        &self,
165        prompt: String,
166    ) -> Pin<Box<dyn Future<Output = ToolDefinition> + Send + Sync + '_>> {
167        Box::pin(<Self as Tool>::definition(self, prompt))
168    }
169
170    fn call(
171        &self,
172        args: String,
173    ) -> Pin<Box<dyn Future<Output = Result<String, ToolError>> + Send + '_>> {
174        Box::pin(async move {
175            match serde_json::from_str(&args) {
176                Ok(args) => <Self as Tool>::call(self, args)
177                    .await
178                    .map_err(|e| ToolError::ToolCallError(Box::new(e)))
179                    .and_then(|output| {
180                        serde_json::to_string(&output).map_err(ToolError::JsonError)
181                    }),
182                Err(e) => Err(ToolError::JsonError(e)),
183            }
184        })
185    }
186}
187
188#[cfg_attr(docsrs, doc(cfg(feature = "rmcp")))]
189#[cfg(feature = "rmcp")]
190pub mod rmcp {
191    use crate::completion::ToolDefinition;
192    use crate::tool::ToolDyn;
193    use crate::tool::ToolError;
194    use rmcp::model::RawContent;
195    use std::borrow::Cow;
196    use std::pin::Pin;
197
198    pub struct McpTool {
199        definition: rmcp::model::Tool,
200        client: rmcp::service::ServerSink,
201    }
202
203    impl McpTool {
204        pub fn from_mcp_server(
205            definition: rmcp::model::Tool,
206            client: rmcp::service::ServerSink,
207        ) -> Self {
208            Self { definition, client }
209        }
210    }
211
212    impl From<&rmcp::model::Tool> for ToolDefinition {
213        fn from(val: &rmcp::model::Tool) -> Self {
214            Self {
215                name: val.name.to_string(),
216                description: val.description.clone().unwrap_or(Cow::from("")).to_string(),
217                parameters: val.schema_as_json_value(),
218            }
219        }
220    }
221
222    impl From<rmcp::model::Tool> for ToolDefinition {
223        fn from(val: rmcp::model::Tool) -> Self {
224            Self {
225                name: val.name.to_string(),
226                description: val.description.clone().unwrap_or(Cow::from("")).to_string(),
227                parameters: val.schema_as_json_value(),
228            }
229        }
230    }
231
232    #[derive(Debug, thiserror::Error)]
233    #[error("MCP tool error: {0}")]
234    pub struct McpToolError(String);
235
236    impl From<McpToolError> for ToolError {
237        fn from(e: McpToolError) -> Self {
238            ToolError::ToolCallError(Box::new(e))
239        }
240    }
241
242    impl ToolDyn for McpTool {
243        fn name(&self) -> String {
244            self.definition.name.to_string()
245        }
246
247        fn definition(
248            &self,
249            _prompt: String,
250        ) -> Pin<Box<dyn Future<Output = ToolDefinition> + Send + Sync + '_>> {
251            Box::pin(async move {
252                ToolDefinition {
253                    name: self.definition.name.to_string(),
254                    description: self
255                        .definition
256                        .description
257                        .clone()
258                        .unwrap_or(Cow::from(""))
259                        .to_string(),
260                    parameters: serde_json::to_value(&self.definition.input_schema)
261                        .unwrap_or_default(),
262                }
263            })
264        }
265
266        fn call(
267            &self,
268            args: String,
269        ) -> Pin<Box<dyn Future<Output = Result<String, ToolError>> + Send + '_>> {
270            let name = self.definition.name.clone();
271            let arguments = serde_json::from_str(&args).unwrap_or_default();
272
273            Box::pin(async move {
274                let result = self
275                    .client
276                    .call_tool(rmcp::model::CallToolRequestParam { name, arguments })
277                    .await
278                    .map_err(|e| McpToolError(format!("Tool returned an error: {e}")))?;
279
280                if let Some(true) = result.is_error {
281                    let error_msg = result
282                        .content
283                        .as_deref()
284                        .and_then(|errors| errors.first())
285                        .and_then(|error| error.as_text())
286                        .map(|raw| raw.text.as_str())
287                        .unwrap_or("No error message returned");
288                    return Err(McpToolError(error_msg.to_string()).into());
289                };
290
291                Ok(result
292                    .content
293                    .into_iter()
294                    .flatten()
295                    .map(|c| match c.raw {
296                        rmcp::model::RawContent::Text(raw) => raw.text,
297                        rmcp::model::RawContent::Image(raw) => {
298                            format!("data:{};base64,{}", raw.mime_type, raw.data)
299                        }
300                        rmcp::model::RawContent::Resource(raw) => match raw.resource {
301                            rmcp::model::ResourceContents::TextResourceContents {
302                                uri,
303                                mime_type,
304                                text,
305                            } => {
306                                format!(
307                                    "{mime_type}{uri}:{text}",
308                                    mime_type = mime_type
309                                        .map(|m| format!("data:{m};"))
310                                        .unwrap_or_default(),
311                                )
312                            }
313                            rmcp::model::ResourceContents::BlobResourceContents {
314                                uri,
315                                mime_type,
316                                blob,
317                            } => format!(
318                                "{mime_type}{uri}:{blob}",
319                                mime_type = mime_type
320                                    .map(|m| format!("data:{m};"))
321                                    .unwrap_or_default(),
322                            ),
323                        },
324                        RawContent::Audio(_) => {
325                            unimplemented!("Support for audio results from an MCP tool is currently unimplemented. Come back later!")
326                        }
327                    })
328                    .collect::<String>())
329            })
330        }
331    }
332}
333
334/// Wrapper trait to allow for dynamic dispatch of raggable tools
335pub trait ToolEmbeddingDyn: ToolDyn {
336    fn context(&self) -> serde_json::Result<serde_json::Value>;
337
338    fn embedding_docs(&self) -> Vec<String>;
339}
340
341impl<T: ToolEmbedding> ToolEmbeddingDyn for T {
342    fn context(&self) -> serde_json::Result<serde_json::Value> {
343        serde_json::to_value(self.context())
344    }
345
346    fn embedding_docs(&self) -> Vec<String> {
347        self.embedding_docs()
348    }
349}
350
351pub(crate) enum ToolType {
352    Simple(Box<dyn ToolDyn>),
353    Embedding(Box<dyn ToolEmbeddingDyn>),
354}
355
356impl ToolType {
357    pub fn name(&self) -> String {
358        match self {
359            ToolType::Simple(tool) => tool.name(),
360            ToolType::Embedding(tool) => tool.name(),
361        }
362    }
363
364    pub async fn definition(&self, prompt: String) -> ToolDefinition {
365        match self {
366            ToolType::Simple(tool) => tool.definition(prompt).await,
367            ToolType::Embedding(tool) => tool.definition(prompt).await,
368        }
369    }
370
371    pub async fn call(&self, args: String) -> Result<String, ToolError> {
372        match self {
373            ToolType::Simple(tool) => tool.call(args).await,
374            ToolType::Embedding(tool) => tool.call(args).await,
375        }
376    }
377}
378
379#[derive(Debug, thiserror::Error)]
380pub enum ToolSetError {
381    /// Error returned by the tool
382    #[error("ToolCallError: {0}")]
383    ToolCallError(#[from] ToolError),
384
385    #[error("ToolNotFoundError: {0}")]
386    ToolNotFoundError(String),
387
388    // TODO: Revisit this
389    #[error("JsonError: {0}")]
390    JsonError(#[from] serde_json::Error),
391}
392
393/// A struct that holds a set of tools
394#[derive(Default)]
395pub struct ToolSet {
396    pub(crate) tools: HashMap<String, ToolType>,
397}
398
399impl ToolSet {
400    /// Create a new ToolSet from a list of tools
401    pub fn from_tools(tools: Vec<impl ToolDyn + 'static>) -> Self {
402        let mut toolset = Self::default();
403        tools.into_iter().for_each(|tool| {
404            toolset.add_tool(tool);
405        });
406        toolset
407    }
408
409    /// Create a toolset builder
410    pub fn builder() -> ToolSetBuilder {
411        ToolSetBuilder::default()
412    }
413
414    /// Check if the toolset contains a tool with the given name
415    pub fn contains(&self, toolname: &str) -> bool {
416        self.tools.contains_key(toolname)
417    }
418
419    /// Add a tool to the toolset
420    pub fn add_tool(&mut self, tool: impl ToolDyn + 'static) {
421        self.tools
422            .insert(tool.name(), ToolType::Simple(Box::new(tool)));
423    }
424
425    pub fn delete_tool(&mut self, tool_name: &str) {
426        let _ = self.tools.remove(tool_name);
427    }
428
429    /// Merge another toolset into this one
430    pub fn add_tools(&mut self, toolset: ToolSet) {
431        self.tools.extend(toolset.tools);
432    }
433
434    pub(crate) fn get(&self, toolname: &str) -> Option<&ToolType> {
435        self.tools.get(toolname)
436    }
437
438    pub async fn get_tool_definitions(&self) -> Result<Vec<ToolDefinition>, ToolSetError> {
439        let mut defs = Vec::new();
440        for tool in self.tools.values() {
441            let def = tool.definition(String::new()).await;
442            defs.push(def);
443        }
444        Ok(defs)
445    }
446
447    /// Call a tool with the given name and arguments
448    pub async fn call(&self, toolname: &str, args: String) -> Result<String, ToolSetError> {
449        if let Some(tool) = self.tools.get(toolname) {
450            tracing::info!(target: "rig",
451                "Calling tool {toolname} with args:\n{}",
452                serde_json::to_string_pretty(&args).unwrap()
453            );
454            Ok(tool.call(args).await?)
455        } else {
456            Err(ToolSetError::ToolNotFoundError(toolname.to_string()))
457        }
458    }
459
460    /// Get the documents of all the tools in the toolset
461    pub async fn documents(&self) -> Result<Vec<completion::Document>, ToolSetError> {
462        let mut docs = Vec::new();
463        for tool in self.tools.values() {
464            match tool {
465                ToolType::Simple(tool) => {
466                    docs.push(completion::Document {
467                        id: tool.name(),
468                        text: format!(
469                            "\
470                            Tool: {}\n\
471                            Definition: \n\
472                            {}\
473                        ",
474                            tool.name(),
475                            serde_json::to_string_pretty(&tool.definition("".to_string()).await)?
476                        ),
477                        additional_props: HashMap::new(),
478                    });
479                }
480                ToolType::Embedding(tool) => {
481                    docs.push(completion::Document {
482                        id: tool.name(),
483                        text: format!(
484                            "\
485                            Tool: {}\n\
486                            Definition: \n\
487                            {}\
488                        ",
489                            tool.name(),
490                            serde_json::to_string_pretty(&tool.definition("".to_string()).await)?
491                        ),
492                        additional_props: HashMap::new(),
493                    });
494                }
495            }
496        }
497        Ok(docs)
498    }
499
500    /// Convert tools in self to objects of type ToolSchema.
501    /// This is necessary because when adding tools to the EmbeddingBuilder because all
502    /// documents added to the builder must all be of the same type.
503    pub fn schemas(&self) -> Result<Vec<ToolSchema>, EmbedError> {
504        self.tools
505            .values()
506            .filter_map(|tool_type| {
507                if let ToolType::Embedding(tool) = tool_type {
508                    Some(ToolSchema::try_from(&**tool))
509                } else {
510                    None
511                }
512            })
513            .collect::<Result<Vec<_>, _>>()
514    }
515}
516
517#[derive(Default)]
518pub struct ToolSetBuilder {
519    tools: Vec<ToolType>,
520}
521
522impl ToolSetBuilder {
523    pub fn static_tool(mut self, tool: impl ToolDyn + 'static) -> Self {
524        self.tools.push(ToolType::Simple(Box::new(tool)));
525        self
526    }
527
528    pub fn dynamic_tool(mut self, tool: impl ToolEmbeddingDyn + 'static) -> Self {
529        self.tools.push(ToolType::Embedding(Box::new(tool)));
530        self
531    }
532
533    pub fn build(self) -> ToolSet {
534        ToolSet {
535            tools: self
536                .tools
537                .into_iter()
538                .map(|tool| (tool.name(), tool))
539                .collect(),
540        }
541    }
542}
543
544#[cfg(test)]
545mod tests {
546    use serde_json::json;
547
548    use super::*;
549
550    fn get_test_toolset() -> ToolSet {
551        let mut toolset = ToolSet::default();
552
553        #[derive(Deserialize)]
554        struct OperationArgs {
555            x: i32,
556            y: i32,
557        }
558
559        #[derive(Debug, thiserror::Error)]
560        #[error("Math error")]
561        struct MathError;
562
563        #[derive(Deserialize, Serialize)]
564        struct Adder;
565
566        impl Tool for Adder {
567            const NAME: &'static str = "add";
568            type Error = MathError;
569            type Args = OperationArgs;
570            type Output = i32;
571
572            async fn definition(&self, _prompt: String) -> ToolDefinition {
573                ToolDefinition {
574                    name: "add".to_string(),
575                    description: "Add x and y together".to_string(),
576                    parameters: json!({
577                        "type": "object",
578                        "properties": {
579                            "x": {
580                                "type": "number",
581                                "description": "The first number to add"
582                            },
583                            "y": {
584                                "type": "number",
585                                "description": "The second number to add"
586                            }
587                        },
588                        "required": ["x", "y"]
589                    }),
590                }
591            }
592
593            async fn call(&self, args: Self::Args) -> Result<Self::Output, Self::Error> {
594                let result = args.x + args.y;
595                Ok(result)
596            }
597        }
598
599        #[derive(Deserialize, Serialize)]
600        struct Subtract;
601
602        impl Tool for Subtract {
603            const NAME: &'static str = "subtract";
604            type Error = MathError;
605            type Args = OperationArgs;
606            type Output = i32;
607
608            async fn definition(&self, _prompt: String) -> ToolDefinition {
609                serde_json::from_value(json!({
610                    "name": "subtract",
611                    "description": "Subtract y from x (i.e.: x - y)",
612                    "parameters": {
613                        "type": "object",
614                        "properties": {
615                            "x": {
616                                "type": "number",
617                                "description": "The number to subtract from"
618                            },
619                            "y": {
620                                "type": "number",
621                                "description": "The number to subtract"
622                            }
623                        },
624                        "required": ["x", "y"]
625                    }
626                }))
627                .expect("Tool Definition")
628            }
629
630            async fn call(&self, args: Self::Args) -> Result<Self::Output, Self::Error> {
631                let result = args.x - args.y;
632                Ok(result)
633            }
634        }
635
636        toolset.add_tool(Adder);
637        toolset.add_tool(Subtract);
638        toolset
639    }
640
641    #[tokio::test]
642    async fn test_get_tool_definitions() {
643        let toolset = get_test_toolset();
644        let tools = toolset.get_tool_definitions().await.unwrap();
645        assert_eq!(tools.len(), 2);
646    }
647
648    #[test]
649    fn test_tool_deletion() {
650        let mut toolset = get_test_toolset();
651        assert_eq!(toolset.tools.len(), 2);
652        toolset.delete_tool("add");
653        assert!(!toolset.contains("add"));
654        assert_eq!(toolset.tools.len(), 1);
655    }
656}
rig/tool.rs

rig/
tool.rs
