fix(openai_mcp_tool_resolve): rewrite type:mcp tools to type:function - #488
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The openai_mcp_tool_resolve filter now rewrites MCP tool entries to function tool entries in the request body before forwarding upstream. This ensures: 1. The proxy always controls MCP execution - upstream never sees type:mcp entries 2. Models emit function_call events that the accumulator can capture into tool_calls for mcp_dispatch to execute 3. All security controls (SSRF validation, auth injection, approval policies) are enforced by the proxy Changes: - Change request_body_access() from ReadOnly to ReadWrite - Add rewrite_request_body() to replace resolved MCP entries with function entries using the prefixed naming scheme (label__tool_name) - Update write_tool_map() to use the rewritten body for ResponsesState so downstream filters see the converted tools - Add Serialization error variant to ResolveError for body rewrite failures - MCP entries without resolved tools (connector_id only, deferred, or no server_url) are preserved unchanged for upstream handling Fixes praxis-proxy#425 Signed-off-by: Sébastien Han <seb@redhat.com>
Refine the type:mcp → type:function rewrite based on review feedback: - Rewrite server-level MCP tool_choice to allowed_tools form scoped to that server's generated functions instead of unrestricted required - Scope collision detection to generated names only so client-supplied duplicate function names pass through to the backend - Pre-build function tools in resolve_all_entries via a consuming pass, eliminating duplication between per_entry and tool_map - Preserve unresolved MCP selectors in allowed_tools tool_choice instead of silently dropping them - Rewrite tool_choice MCP selectors inside allowed_tools compound form - Document the server_label__tool_name encoding rationale Signed-off-by: Sébastien Han <seb@redhat.com>
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franciscojavierarceo
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…#488) * fix(openai_mcp_tool_resolve): rewrite type:mcp tools to type:function The openai_mcp_tool_resolve filter now rewrites MCP tool entries to function tool entries in the request body before forwarding upstream. This ensures: 1. The proxy always controls MCP execution - upstream never sees type:mcp entries 2. Models emit function_call events that the accumulator can capture into tool_calls for mcp_dispatch to execute 3. All security controls (SSRF validation, auth injection, approval policies) are enforced by the proxy Changes: - Change request_body_access() from ReadOnly to ReadWrite - Add rewrite_request_body() to replace resolved MCP entries with function entries using the prefixed naming scheme (label__tool_name) - Update write_tool_map() to use the rewritten body for ResponsesState so downstream filters see the converted tools - Add Serialization error variant to ResolveError for body rewrite failures - MCP entries without resolved tools (connector_id only, deferred, or no server_url) are preserved unchanged for upstream handling Fixes #425 Signed-off-by: Sébastien Han <seb@redhat.com> * fix(openai_mcp_tool_resolve): address review findings for MCP rewrite Refine the type:mcp → type:function rewrite based on review feedback: - Rewrite server-level MCP tool_choice to allowed_tools form scoped to that server's generated functions instead of unrestricted required - Scope collision detection to generated names only so client-supplied duplicate function names pass through to the backend - Pre-build function tools in resolve_all_entries via a consuming pass, eliminating duplication between per_entry and tool_map - Preserve unresolved MCP selectors in allowed_tools tool_choice instead of silently dropping them - Rewrite tool_choice MCP selectors inside allowed_tools compound form - Document the server_label__tool_name encoding rationale Signed-off-by: Sébastien Han <seb@redhat.com> --------- Signed-off-by: Sébastien Han <seb@redhat.com>
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Summary
Closes #425.
The
openai_mcp_tool_resolvefilter now rewritestype: "mcp"tool entries in the Responses API request body totype: "function"before forwarding upstream, since inference backends have no concept of MCP tools.tools/list, builds a dispatch map (mcp_tool_map), and replaces MCP entries with function tools using{server_label}__{tool_name}encoding for unique dispatchtool_choiceMCP references: named MCP → function, server-level MCP →allowed_toolsscoped to that server, MCP selectors insideallowed_tools→ expanded function refs (unresolved selectors are preserved)tool_choiceintoResponsesStatefor downstream filterstool_choicetranslation, and state syncTest plan
cargo test -p praxis-ai-apis -- openai_mcp_tool_resolve— 87 tests passmake lint— clippy, rustfmt, separator, and filter-doc checks passmcp_tools_rewritten_to_function_typevalidates end-to-end rewrite