fix(mcp): drop top-level oneOf from context tool schema

[balcsida]

Summary

The MCP context tool could not be loaded through OpenAI-compatible function calling (Azure OpenAI via LiteLLM). Its input schema expressed the uid-or-name choice as a top-level oneOf, which those APIs reject:

Invalid schema for function 'graphnest_context': schema must have type 'object' and not have 'oneOf'/'anyOf'/'allOf'/'enum'/'const'/'not' at the top level.

Because the full tool list is sent with every request, one rejected schema failed every call, across every fallback model.

Changes

• Remove the top-level oneOf from the context tool schema. The service already rejects requests with neither or both of uid and name (internal/graphservice/context.go), so validation is unchanged. The tool description now states the rule so models still learn it.
• Add TestToolSchemasAcceptedByFunctionCalling, which registers every tool (search, repositories, SCIP, graph, supply chain) and asserts each input schema is a plain object with no top-level oneOf/anyOf/allOf/enum/const/not. It fails on the previous schema.
• Changelog entry under Unreleased.

No configuration, schema, or security implications.

Verification

go vet ./internal/mcpserver/
go test ./internal/mcpserver/

🤖 Generated with Claude Code