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Version: v2.0

Tools (Function Calling)

Tools define functions that can be invoked within the Spice runtime, either directly or by a language model (LLMs). These tools provide access to different functionalities and can be customized in the tools section of spicepod.yaml.

tools​

The tools section in your configuration specifies one or more tools available for use in the runtime.

Example:

tools:
  - name: my_mcp_tool
    from: mcp:http://localhost:8090/v1/mcp
    description: 'An MCP tool.'

name​

A unique identifier for this tool.

from​

Defines the source of the tool, or the specific built-in tool to customise. See Available Tools for a list of available tools.

For MCP tools, the target is part of the from value itself, in the form mcp:<target>:

  • mcp:<url> connects to an MCP server over Streamable HTTP, e.g. mcp:http://localhost:8090/v1/mcp.
  • mcp:<command> runs a stdio-based MCP server as a subprocess, e.g. mcp:npx.

A bare from: mcp (without a :<target> suffix) is rejected when the spicepod is loaded.

description​

Optional. A textual description of the tool's function.

params​

Optional. A map of key-value pairs for additional parameters specific to the tool. For MCP tools these are mcp_args (stdio), and mcp_auth_token / mcp_headers (Streamable HTTP) — see MCP Tools. The MCP server address is set via from, not via params.

env​

Optional. A map of key-value pairs of arbitrary environment variables to set when running the tool. Only useable if the tool requires a subprocess to run (e.g. MCP over stdio) .

dependsOn​

Optional. A list of dependencies that must be available before this tool can be used.