Tool description
Describe both what it does and what it does not.
Names, purposes, context and preconditions help callers choose correctly. A tool should have a specific job.
Open source · Plugins & connectorsOpen the reference connector
Give your tools
a place in the next step.
A clear tool description. Inputs that can be checked. Outputs another system can use. Connectors give systems a shared language for working together.
DISCOVERVALIDATE
CONNECT
CallerMCP
Client
Client
catalog.describe
One tool. One contract.
Input
datasetHandle
read-onlyOutput
schema + metadataUnderstand the connection
from end to end.
MCP Catalog Kit exposes the schemas of two synthetic datasets through one read-only tool. Change the dataset to inspect its arguments and result. The archive includes the same local example.
catalog.describeSample data · Local contract preview
Request arguments
{
"name": "catalog.describe",
"arguments": {
"dataset": "orders"
}
}Only listed datasets are accepted. Extra arguments are rejected.
Returned schema
3 synthetic rows| Field | Type |
|---|---|
order_id | string |
region | string |
amount | number |
readOnlyHintstructuredContent
This preview uses local sample mappings, not your database. Tool hints do not replace authorization checks in a real system.
MCP Catalog Kitv0.1.0 · Node.js 20+ · MCP 2025-11-25 · MIT
Download connector sourceZIP · 4.6 KBA plugin can be small.
Its contract must be clear.
Moving from a local example to a business connector means specifying the responsibility of each call, not merely changing an address.
Input & access
Check argument structure and caller access separately.
Type checks are not authorization. Define access by identity, data scope and action; keep credentials in a controlled runtime.
Output & errors
Make the next step unambiguous.
Return understandable structures and distinguish invalid arguments, execution failures and unmet business conditions.
Bring the connection
into your own terminal.
Unpack the archive and run the commands inside it. The example initializes, discovers a tool and reads a catalogue. Tests cover initialization, invalid arguments and unknown datasets.
No dependencies · No credentials
node server.mjs < requests.jsonl
node --test server.test.mjsScope: stdio and one read-only tool. Production integration needs authentication, monitoring, version compatibility and business access control.
Read the full README ↗Go deeper into the protocol.
LifecycleInitialization and negotiationTransportStdio and message boundariesToolsDiscovery, invocation and results
The reference is pinned to MCP 2025-11-25. These links point to that version of the official specification.