# Tool Modifiers Implementation
## Overview
This document describes the implementation of tool modifiers in the Composio Rust SDK, translated from the Python SDK's `_modifiers.py` module.
## Architecture
### Core Components
1. **Modifier Traits** - Define the interface for different modifier types
2. **Modifier Struct** - Encapsulates modifier logic and metadata
3. **Helper Functions** - Apply modifiers to tool execution pipeline
### File Structure
```
src/models/
├── modifiers.rs # Main implementation
└── mod.rs # Module exports
examples/
└── modifiers_usage.rs # Usage examples
```
## Modifier Types
### 1. BeforeExecute
Modifies tool execution parameters before the tool is executed.
**Use Cases:**
- Inject default values
- Add authentication headers
- Validate or transform input parameters
- Add metadata or tracking information
**Trait Definition:**
```rust
pub trait BeforeExecute: Send + Sync {
fn modify(&self, tool: &str, toolkit: &str, params: ToolExecuteParams) -> ToolExecuteParams;
}
```
**Example:**
```rust
struct InjectLabelsModifier;
impl BeforeExecute for InjectLabelsModifier {
fn modify(&self, tool: &str, toolkit: &str, mut params: ToolExecuteParams) -> ToolExecuteParams {
if tool == "GITHUB_CREATE_ISSUE" {
params.arguments.insert(
"labels".to_string(),
serde_json::json!(["automated"]),
);
}
params
}
}
let modifier = Modifier::before_execute(
vec!["GITHUB_CREATE_ISSUE".to_string()],
vec![],
InjectLabelsModifier,
);
```
### 2. AfterExecute
Modifies tool execution response after the tool has executed.
**Use Cases:**
- Transform response format
- Filter sensitive data
- Add computed fields
- Log execution results
- Truncate large responses
**Trait Definition:**
```rust
pub trait AfterExecute: Send + Sync {
fn modify(
&self,
tool: &str,
toolkit: &str,
response: ToolExecutionResponse,
) -> ToolExecutionResponse;
}
```
**Example:**
```rust
struct LogResultModifier;
impl AfterExecute for LogResultModifier {
fn modify(
&self,
tool: &str,
toolkit: &str,
response: ToolExecutionResponse,
) -> ToolExecutionResponse {
println!("Tool {}/{} executed: {}", toolkit, tool, response.successful);
response
}
}
let modifier = Modifier::after_execute(
vec![], // Apply to all tools
vec!["github".to_string()],
LogResultModifier,
);
```
### 3. SchemaModifier
Modifies tool schema before it's presented to the AI agent.
**Use Cases:**
- Customize tool descriptions
- Add/remove parameters
- Change parameter requirements
- Add examples or hints
- Simplify complex schemas
**Trait Definition:**
```rust
pub trait SchemaModifier: Send + Sync {
fn modify(&self, tool: &str, toolkit: &str, schema: ToolSchema) -> ToolSchema;
}
```
**Example:**
```rust
struct EnhanceDescriptionModifier;
impl SchemaModifier for EnhanceDescriptionModifier {
fn modify(&self, tool: &str, toolkit: &str, mut schema: ToolSchema) -> ToolSchema {
schema.description = format!("[Enhanced] {}", schema.description);
schema
}
}
let modifier = Modifier::schema(
vec!["GITHUB_CREATE_ISSUE".to_string()],
vec![],
EnhanceDescriptionModifier,
);
```
### 4. BeforeExecuteMeta
Modifies parameters before meta tool execution in a session context.
**Use Cases:**
- Add session-specific context
- Inject session state
- Validate session permissions
- Add session metadata
**Trait Definition:**
```rust
pub trait BeforeExecuteMeta: Send + Sync {
fn modify(
&self,
tool: &str,
toolkit: &str,
session_id: &str,
params: HashMap<String, serde_json::Value>,
) -> HashMap<String, serde_json::Value>;
}
```
### 5. AfterExecuteMeta
Modifies response after meta tool execution in a session context.
**Use Cases:**
- Update session state
- Cache results
- Track session metrics
- Transform session-specific data
**Trait Definition:**
```rust
pub trait AfterExecuteMeta: Send + Sync {
fn modify(
&self,
tool: &str,
toolkit: &str,
session_id: &str,
response: ToolExecutionResponse,
) -> ToolExecutionResponse;
}
```
## Modifier Filtering
Modifiers can be scoped to specific tools or toolkits:
### Apply to Specific Tools
```rust
let modifier = Modifier::before_execute(
vec!["GITHUB_CREATE_ISSUE".to_string(), "GITHUB_UPDATE_ISSUE".to_string()],
vec![],
MyModifier,
);
```
### Apply to Specific Toolkits
```rust
let modifier = Modifier::after_execute(
vec![],
vec!["github".to_string(), "gitlab".to_string()],
MyModifier,
);
```
### Apply to All Tools
```rust
let modifier = Modifier::schema(
vec![], // Empty = all tools
vec![], // Empty = all toolkits
MyModifier,
);
```
## Usage Pattern
### 1. Create Modifiers
```rust
let modifiers = vec![
Modifier::before_execute(
vec!["GITHUB_CREATE_ISSUE".to_string()],
vec![],
InjectLabelsModifier,
),
Modifier::after_execute(
vec![],
vec!["github".to_string()],
LogResultModifier,
),
Modifier::schema(
vec!["GITHUB_CREATE_ISSUE".to_string()],
vec![],
EnhanceDescriptionModifier,
),
];
```
### 2. Apply Modifiers
```rust
use composio_sdk::models::{
apply_before_execute_modifiers,
apply_after_execute_modifiers,
apply_schema_modifiers,
};
// Before execution
let params = apply_before_execute_modifiers(
&modifiers,
"GITHUB_CREATE_ISSUE",
"github",
params,
)?;
// After execution
let response = apply_after_execute_modifiers(
&modifiers,
"GITHUB_CREATE_ISSUE",
"github",
response,
)?;
// Schema modification
let schema = apply_schema_modifiers(
&modifiers,
"GITHUB_CREATE_ISSUE",
"github",
schema,
)?;
```
## Key Differences from Python Implementation
### 1. Type Safety
- Rust uses traits instead of Protocol
- Compile-time type checking
- No runtime type errors
### 2. Ownership and Borrowing
- Modifiers take ownership of data
- No need for explicit cloning in most cases
- Memory safety guaranteed by compiler
### 3. Error Handling
- Returns `Result<T, String>` instead of raising exceptions
- Explicit error propagation with `?` operator
- No silent failures
### 4. Concurrency
- `Send + Sync` bounds ensure thread safety
- Can be used safely in async contexts
- No GIL limitations
### 5. Function Overloading
- Rust doesn't support function overloading
- Separate constructor methods for each modifier type
- More explicit API
## Integration Points
### Session Management
Modifiers can be integrated with the Session API:
```rust
// Future integration
session.with_modifiers(modifiers)
.execute_tool("GITHUB_CREATE_ISSUE", params)
.await?;
```
### Tool Execution
Modifiers are applied in the tool execution pipeline:
```rust
// 1. Apply schema modifiers (when fetching tools)
let schema = apply_schema_modifiers(&modifiers, tool, toolkit, schema)?;
// 2. Apply before execute modifiers
let params = apply_before_execute_modifiers(&modifiers, tool, toolkit, params)?;
// 3. Execute tool
let response = execute_tool(params).await?;
// 4. Apply after execute modifiers
let response = apply_after_execute_modifiers(&modifiers, tool, toolkit, response)?;
```
## Testing
Run the example to see modifiers in action:
```bash
cargo run --example modifiers_usage
```
Expected output demonstrates:
1. Parameter injection (BeforeExecute)
2. Response logging (AfterExecute)
3. Schema enhancement (SchemaModifier)
4. Modifier filtering by tool/toolkit
## Future Enhancements
### 1. Async Modifiers
Support async operations in modifiers:
```rust
#[async_trait]
pub trait AsyncBeforeExecute: Send + Sync {
async fn modify(&self, tool: &str, toolkit: &str, params: ToolExecuteParams)
-> ToolExecuteParams;
}
```
### 2. Modifier Composition
Chain multiple modifiers:
```rust
let composed = modifier1.and_then(modifier2);
```
### 3. Conditional Modifiers
Apply modifiers based on conditions:
```rust
let modifier = Modifier::before_execute(...)
.when(|tool, toolkit| toolkit == "github");
```
### 4. Modifier Middleware
Stack-based modifier execution:
```rust
let middleware = ModifierMiddleware::new()
.use_modifier(modifier1)
.use_modifier(modifier2);
```
## Comparison with Python SDK
| Type Safety | Runtime (Protocol) | Compile-time (Trait) |
| Error Handling | Exceptions | Result<T, E> |
| Concurrency | GIL limited | Native async/await |
| Memory Safety | GC | Ownership system |
| Performance | Interpreted | Compiled |
| Decorator Support | @decorator | Builder pattern |
| Function Overloading | Yes | No (separate methods) |
## References
- Python implementation: `temp/composio/core/models/_modifiers.py`
- Rust implementation: `src/models/modifiers.rs`
- Usage example: `examples/modifiers_usage.rs`
- Documentation: File 06 in Composio docs (Direct Tool Execution Guides)