feat: add MCP tool integration#1042
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ajbozarth merged 2 commits intoMay 11, 2026
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Adds mellea/stdlib/tools/mcp.py, a new module that bridges MCP server tools into Mellea's native tool-calling system. MCPToolSpec.as_mellea_tool() wraps each discovered tool as a MelleaTool ready to pass via ModelOption.TOOLS or to react(). Public API: - discover_mcp_tools(connection) -> list[MCPToolSpec] - MCPToolSpec.as_mellea_tool() -> MelleaTool - http_connection, sse_connection, stdio_connection helpers Each tool invocation opens a short-lived MCP session and runs on mellea's shared background event loop via _run_async_in_thread, so callers do not need to manage session lifetime. Verified end-to-end against the hosted GitHub MCP server. Adds mcp>=1.27.0 and httpx>=0.27 to the mellea[tools] extra. httpx is already transitive via smolagents and langchain-core. Assisted-by: Claude Code Signed-off-by: Alex Bozarth <ajbozart@us.ibm.com>
This was referenced May 8, 2026
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cc @akihikokuroda @psschwei @planetf1 @jakelorocco as reviewers from the original contribs PR |
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All the feedback from the contribs review is addressed — timeouts are now configurable with sensible defaults, all five content types are handled, and as_mellea_tool() is correctly typed. A few nits inline, nothing blocking.
- Add return type annotation to `_open_session`. - Log swallowed exceptions in the `ResourceLink` fallback path at debug level instead of discarding them silently. - Drop redundant `_connection` private-attribute assertion in tests; wiring is already covered by the `_open_session` mocks used throughout. Assisted-by: Claude Code Signed-off-by: Alex Bozarth <ajbozart@us.ibm.com>
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@planetf1 addressed your nits, I'll hold off on merge for a bit to let anyone else re-review after the PR move from contribs to mellea. Otherwise I'll merge this as is at EOD |
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May 11, 2026
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Tool PR
Description
Adds
mellea/stdlib/tools/mcp.py, bridging MCPserver tools into Mellea's native tool-calling system. Any MCP server's tools
can now be discovered and used inside a Mellea agent.
Public API:
discover_mcp_tools(connection) -> list[MCPToolSpec]MCPToolSpec.as_mellea_tool() -> MelleaToolhttp_connection,sse_connection,stdio_connectiontransport helpersRuntime: each tool invocation opens a short-lived MCP session and runs on
mellea's shared background event loop via
_run_async_in_thread. Verifiedend-to-end against the hosted GitHub MCP server.
Deps:
mcp>=1.27.0andhttpx>=0.27added to themellea[tools]extra.httpxis already transitive viasmolagentsandlangchain-core.Supersedes
mellea-contribs#54,which will be closed rather than merged. Jake suggested during review
that this belongs in core.
Issue #1032 point 2 (generalizing the async-to-sync wrapper onto
MelleaTool.from_callable) is handled by #1041.Implementation Checklist
Protocol Compliance
MelleaToolinstances via the constructor; no backend changes required.Integration
mellea/stdlib/tools/__init__.pyor, if you are adding a library of components, from your sub-modulemellea.stdlib.tools.mcpsubmodule. Not added to__init__.pybecause the module importsmcpandhttpxat top level and should only be loaded when thetoolsextra is installed.Testing
tests/stdlib/tools/Attribution