Report MCP toolkit failures before recovery

[ebramanti]

Type

• Refactor
• Feature
• Bug Fix
• Optimization
• Documentation Update

Description

McpServer.registerToolkit converts tool failures and defects into safe MCP error results before the outer HTTP or RPC reporting boundaries can observe their original Cause. As a result, configured ErrorReporters do not receive failures that the MCP server subsequently recovers.

This change:

• applies Effect.withErrorReporting after tool execution and result serialization, but before MCP error recovery
• runs reporting with the context captured during toolkit registration
• preserves existing public CallToolResult messages and protocol behavior
• adds coverage for declared failures, defects, response-serialization defects, and successful calls
• includes a patch changeset

Validation:

• pnpm test --run packages/effect/test/unstable/ai/McpServer/McpServer.test.ts
• pnpm lint-fix
• pnpm check

Related

• Related: Prevent MCP tool errors from exposing internals #6607
• Closes: N/A

[changeset-bot]

🦋 Changeset detected

Latest commit: 55e2993

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 30 packages

Name	Type
effect	Patch
@effect/ai-anthropic	Patch
@effect/ai-openai	Patch
@effect/ai-openai-compat	Patch
@effect/ai-openrouter	Patch
@effect/atom-react	Patch
@effect/atom-solid	Patch
@effect/atom-vue	Patch
@effect/docgen	Patch
@effect/doctest	Patch
@effect/openapi-generator	Patch
@effect/opentelemetry	Patch
@effect/platform-browser	Patch
@effect/platform-bun	Patch
@effect/platform-deno	Patch
@effect/platform-node	Patch
@effect/platform-node-shared	Patch
@effect/sql-clickhouse	Patch
@effect/sql-d1	Patch
@effect/sql-libsql	Patch
@effect/sql-mssql	Patch
@effect/sql-mysql2	Patch
@effect/sql-pg	Patch
@effect/sql-pglite	Patch
@effect/sql-sqlite-bun	Patch
@effect/sql-sqlite-do	Patch
@effect/sql-sqlite-node	Patch
@effect/sql-sqlite-react-native	Patch
@effect/sql-sqlite-wasm	Patch
@effect/vitest	Patch

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[github-actions]

Bundle Size Analysis

Generated from PR build output; treat the content below as untrusted.

File Name	Current Size	Previous Size	Difference
arbitrary-combinators.ts	33.76 KB	33.76 KB	0.00 KB (0.00%)
basic.ts	7.00 KB	7.00 KB	0.00 KB (0.00%)
batching.ts	9.87 KB	9.87 KB	0.00 KB (0.00%)
brand.ts	6.56 KB	6.56 KB	0.00 KB (0.00%)
cache.ts	10.74 KB	10.74 KB	0.00 KB (0.00%)
config.ts	21.45 KB	21.45 KB	0.00 KB (0.00%)
differ.ts	20.32 KB	20.32 KB	0.00 KB (0.00%)
http-client.ts	21.76 KB	21.76 KB	0.00 KB (0.00%)
logger.ts	10.94 KB	10.94 KB	0.00 KB (0.00%)
metric.ts	8.98 KB	8.98 KB	0.00 KB (0.00%)
optic.ts	6.73 KB	6.73 KB	0.00 KB (0.00%)
pubsub.ts	15.12 KB	15.12 KB	0.00 KB (0.00%)
queue.ts	11.84 KB	11.84 KB	0.00 KB (0.00%)
schedule.ts	10.86 KB	10.86 KB	0.00 KB (0.00%)
schema-binary.ts	39.42 KB	39.42 KB	0.00 KB (0.00%)
schema-class.ts	20.07 KB	20.07 KB	0.00 KB (0.00%)
schema-fromJsonSchemaDocument.ts	31.02 KB	31.02 KB	0.00 KB (0.00%)
schema-representation-roundtrip.ts	26.21 KB	26.21 KB	0.00 KB (0.00%)
schema-string-transformation.ts	13.66 KB	13.66 KB	0.00 KB (0.00%)
schema-string.ts	11.18 KB	11.18 KB	0.00 KB (0.00%)
schema-template-literal.ts	15.47 KB	15.47 KB	0.00 KB (0.00%)
schema-toArbitrary.ts	33.31 KB	33.31 KB	0.00 KB (0.00%)
schema-toCodeDocument.ts	24.51 KB	24.51 KB	0.00 KB (0.00%)
schema-toCodecJson.ts	19.29 KB	19.29 KB	0.00 KB (0.00%)
schema-toEquivalence.ts	19.42 KB	19.42 KB	0.00 KB (0.00%)
schema-toFormatter.ts	19.51 KB	19.51 KB	0.00 KB (0.00%)
schema-toJsonSchemaDocument.ts	23.45 KB	23.45 KB	0.00 KB (0.00%)
schema-toRepresentation.ts	19.56 KB	19.56 KB	0.00 KB (0.00%)
schema.ts	19.28 KB	19.28 KB	0.00 KB (0.00%)
stm.ts	12.74 KB	12.74 KB	0.00 KB (0.00%)
stream.ts	9.83 KB	9.83 KB	0.00 KB (0.00%)