mcp-schema-registry client

The mcp-schema-registry client binding exposes a Karapace-compatible schema registry's subject, schema, and compatibility operations as a fixed set of intrinsic MCP tools, connecting directly to the registry named by options.server — unlike mcp-openapi, there is no upstream spec or per-tool schema to author. mcp-kafka and mcp-kafka-connect follow the same fixed-tool pattern for the Kafka broker and Kafka Connect REST APIs.

mcp_schema_registry_client:
  type: mcp-schema-registry
  kind: client
  options:
    server: http://karapace-registry.examples.dev:8081
  routes:
    - when:
        - tool: register_schema
      guarded:
        my_guard:
          - kafka-sr:write
    - when:
        - tool: "*"

Configuration (* required)

options*

object

The client specific options.

options:
  server: http://karapace-registry.examples.dev:8081

options.server*

string

Base URL of the schema registry this binding proxies to.

routes*

array of object

Conditional mcp-schema-registry specific routes, matching by tool name or glob pattern. At least one route is required. Routes are evaluated in order; the first matching route wins.

routes:
  - when:
      - tool: register_schema
    guarded:
      my_guard:
        - kafka-sr:write
  - when:
      - tool: "*"

routes[].when*

array of object

List of conditions (any match) restricting this route to particular tools. Required.

routes:
  - when:
      - tool: register_schema
      - tool: set_compatibility

when[].tool*

string or array of string

Tool name matched by tools/call, or a * glob pattern matching many tool names in bulk (such as list_*). Required.

routes[].guarded

object as map of named array of string

Roles required by the named guard for a tools/call against this route. Roles for the same guard are unioned into one entry; roles naming a different guard add a separate entry that must also authorize.

routes:
  - when:
      - tool: register_schema
    guarded:
      my_guard:
        - kafka-sr:write

telemetry

object

Defines the desired telemetry for the binding.

telemetry.metrics

array

Telemetry metrics to track

telemetry:
  metrics:
    - stream.*

telemetry.attributes

object as map of named string properties

Telemetry attributes to add to the binding metrics.

Tools

The mcp-schema-registry client exposes a fixed set of intrinsic tools, derived from a bundled schema registry API specification — there is no options.tools to author, and no upstream server or spec to select. Each tool's inputSchema validates tools/call arguments before Zilla dispatches the matching request to options.server. None of these tools declare a fixed outputSchema, so each tool's structuredContent mirrors the raw upstream JSON response with no fixed property list, and its summary text may interpolate fields out of that same response, such as ${result.id}.

list_subjects

Read-only, idempotent

Lists every subject registered in the schema registry.

No arguments.

The result's structuredContent mirrors the raw upstream JSON response — an array of subject names.

describe_subject

Read-only, idempotent

Lists the schema version numbers registered for a subject.

Argument	Type	Required	Description
`subject`	`string`	Yes	Subject to list versions for.

The result's structuredContent mirrors the raw upstream JSON response — an array of version numbers.

register_schema

Not destructive, not idempotent

Registers a new schema version under a subject.

Argument	Type	Required	Description
`subject`	`string`	Yes	Subject to register the schema under.
`schema`	`string`	No	Schema document to register.
`schemaType`	`string`	No	Schema format, such as `AVRO`, `JSON`, or `PROTOBUF`. Defaults to `AVRO` when omitted.

The summary interpolates ${result.id}, such as Registered schema with id 1.

get_schema

Read-only, idempotent

Retrieves a specific registered schema version for a subject.

Argument	Type	Required	Description
`subject`	`string`	Yes	Subject to read from.
`version`	`string`	Yes	Schema version number, or `latest`.

The summary interpolates ${result.id} and ${result.version}, such as Retrieved schema id 1, version 1.

delete_schema_version

Destructive, idempotent

Deletes a specific registered schema version for a subject.

Argument	Type	Required	Description
`subject`	`string`	Yes	Subject to delete from.
`version`	`string`	Yes	Schema version number, or `latest`.

delete_subject

Destructive, idempotent

Deletes a subject and every schema version registered under it.

Argument	Type	Required	Description
`subject`	`string`	Yes	Subject to delete.

The result's structuredContent mirrors the raw upstream JSON response — an array of the deleted subject's version numbers.

check_compatibility

Read-only, idempotent

Checks whether a schema is compatible with a specific already-registered version of a subject.

Argument	Type	Required	Description
`subject`	`string`	Yes	Subject to check compatibility against.
`version`	`string`	Yes	Schema version number, or `latest`, to check compatibility against.
`schema`	`string`	No	Schema document to check.
`schemaType`	`string`	No	Schema format, such as `AVRO`, `JSON`, or `PROTOBUF`. Defaults to `AVRO` when omitted.

The summary interpolates ${result.is_compatible}, such as Compatibility check result: true.

get_compatibility

Read-only, idempotent

Reads the compatibility level configured for a subject.

Argument	Type	Required	Description
`subject`	`string`	Yes	Subject to read the compatibility level of.

The summary interpolates ${result.compatibilityLevel}, such as Compatibility level is FULL.

set_compatibility

Not destructive, idempotent

Sets the compatibility level for a subject.

Argument	Type	Required	Description
`subject`	`string`	Yes	Subject to set the compatibility level of.
`compatibility`	`string`	No	Compatibility level, such as `BACKWARD`, `FORWARD`, `FULL`, or `NONE`.

The summary interpolates ${result.compatibility}, such as Compatibility level set to FULL.