MCP tool input schemas are now validated against JSON Schema draft 2020-12. Tools with schemas that violate Anthropic API requirements are excluded when the server's tools are loaded; a system message lists which tools were dropped.
- Added
$dynamicAnchorand$dynamicRef(replacing the deprecated$recursiveAnchor/$recursiveRef) - Added
dependentRequiredanddependentSchemas(splitting the olddependencieskeyword) - Added
maxContainsandminContains - Added complete draft 2020-12 meta-schemas for core, validation, meta-data, format-annotation, content, applicator, and unevaluated vocabularies
tengu_mcp_normalize_root_combinatorsis a per-server-URL feature flag (configured as a list of hostnames, or"*"for all servers): when enabled for a server, tools whose input schema has a top-levelanyOf,oneOf, orallOfkeyword are flattened — properties are merged from all combinator branches into a single flatpropertiesobject, required fields are collected from every branch, and a plain-text constraint note summarising the original branches is prepended to the tool's description. Without this flag, tools with top-level combinators are skipped entirely and logged astool_schema_normalize_gated.tengu_mcp_drop_invalid_tool_schemasis a per-server-URL feature flag: when enabled, tools whose input schema fails draft 2020-12 meta-validation (checked via an Ajv2020 meta-validator) or whose property keys do not match/^[a-zA-Z0-9_.-]{1,64}$/are excluded from the tool list and added to adroppedToolslist that feeds the "Unavailable MCP Tools" system reminder. Without this flag, such tools are kept but a debug warning is logged that API requests including them may fail.- A system-reminder block titled "Unavailable MCP Tools" lists each excluded tool and its rejection reason
New validator module (search for "https://json-schema.org/draft/2020-12/meta/core" or "$dynamicAnchor"). Exclusion message (search for "# Unavailable MCP Tools").
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
tengu_mcp_normalize_root_combinators Not enough to sayNothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.
This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.216: not a boolean we can read
These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.
tengu_mcp_drop_invalid_tool_schemas Not enough to sayNothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.
This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.216: not a boolean we can read
These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.
Read once, for one account on one subscription tier, against v2.1.216. It isn't a statement about your account. What a flag value here can and cannot tell you
A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.