[mudler-agent]

Summary

Preserve the official MCP SDK's complete Tool.InputSchema as json.RawMessage when constructing model-facing tool parameters.

The previous conversion through LangChainGo's jsonschema.Definition loses keywords that the struct cannot represent. For example, a nullable enum expressed with anyOf becomes {"properties":{}}. Its enum and default disappear. Root references, definitions, and compositions can disappear too.

MCP discovery now forwards the schema without that conversion or nullable/boolean coercion. The exported CoerceNullableTypes helper remains available, deprecated and isolated from discovery, for existing callers.

Tests

• Add discovery regressions for nullable enums, explicit defaults, references, compositions, boolean subschemas, constraints, and absent properties.
• Add eight HTTP serialization cases for OpenAI and LocalAI, covering streaming, completion, metadata, and native-media paths.
• Replace the obsolete expectation that discovery inserts empty properties.

Verification commands (all pass):

go test . -count=1 -args -ginkgo.label-filter='!e2e'
go test ./clients ./examples/... ./prompt ./structures ./tests/... -count=1
go test -race . ./clients -run 'Test(MCPDiscoveryPreservesInputSchema|ClientsPreserveRawToolSchema|Coerce|BooleanSchema|Normalization)' -count=1

The corrected regression tests fail before the implementation. Independent review and a separate non-e2e test run pass.

Scope

No dependency upgrade or broader LLM migration. The default MCP path preserves schemas; opt-in strict-tool mode retains its existing transformations. HTTP tests use local mock servers, not external model services.