Trait SchemaAdapter

Source

pub trait SchemaAdapter:
    Send
    + Sync
    + Debug {
    // Required method
    fn normalize_schema(&self, schema: Value) -> Value;

    // Provided methods
    fn normalize_tool_name<'a>(&self, name: &'a str) -> Cow<'a, str> { ... }
    fn empty_schema(&self) -> Value { ... }
}

Expand description

Core traits and types.

Always available regardless of feature flags. Includes:

Agent - The fundamental trait for all agents
Tool / Toolset - For extending agents with capabilities
Session / State - For managing conversation context
Event - For streaming agent responses
AdkError / Result - Unified error handling Normalizes JSON Schema for a specific LLM provider’s function-calling API.

Each provider has different schema requirements. The adapter transforms raw MCP tool schemas into the provider’s accepted format at request time.

§Default Implementations

normalize_tool_name: Truncates names exceeding 64 bytes at a valid UTF-8 character boundary.
empty_schema: Returns {"type": "object", "properties": {}} as the fallback when no input schema is provided.

§Thread Safety

All implementations must be Send + Sync to support concurrent request building across async tasks.

Required Methods§

Source

fn normalize_schema(&self, schema: Value) -> Value

Normalize a raw JSON Schema for this provider.

Called once per tool per request (results may be cached by the model adapter layer).

§Arguments

schema - The raw JSON Schema value from an MCP tool’s inputSchema.

§Returns

A normalized JSON Schema value accepted by this provider’s API.

Provided Methods§

Source

fn normalize_tool_name<'a>(&self, name: &'a str) -> Cow<'a, str>

Normalize a tool name for this provider’s limits.

Default implementation truncates names exceeding 64 bytes at the nearest valid UTF-8 character boundary, preserving the prefix.

§Arguments

name - The original tool name.

§Returns

A Cow::Borrowed reference if the name fits within 64 bytes, or a Cow::Owned truncated string otherwise.

§Example

use adk_core::SchemaAdapter;
use serde_json::Value;
use std::borrow::Cow;

#[derive(Debug)]
struct TestAdapter;
impl SchemaAdapter for TestAdapter {
    fn normalize_schema(&self, schema: Value) -> Value { schema }
}

let adapter = TestAdapter;

// Short names are returned as-is
assert_eq!(adapter.normalize_tool_name("get_weather"), Cow::Borrowed("get_weather"));

// Long names are truncated to at most 64 bytes
let long_name = "a".repeat(100);
let result = adapter.normalize_tool_name(&long_name);
assert!(result.len() <= 64);

Source

fn empty_schema(&self) -> Value

Fallback schema when a tool provides no parameters_schema.

Returns {"type": "object", "properties": {}} by default, which represents a tool that accepts no parameters.

§Example

use adk_core::SchemaAdapter;
use serde_json::{json, Value};

#[derive(Debug)]
struct TestAdapter;
impl SchemaAdapter for TestAdapter {
    fn normalize_schema(&self, schema: Value) -> Value { schema }
}

let adapter = TestAdapter;
assert_eq!(adapter.empty_schema(), json!({"type": "object", "properties": {}}));