catalog_getRetrieve a single record from a JSON catalog by its id. Returns the record and a found flag, enabling direct access to specific items.
Fetch a single record by its key field ("id"). Returns { found, record }.
| Name | Required | Description | Default |
|---|---|---|---|
| key | Yes | Value of the record's "id" field. Numbers are matched loosely. | |
| fields | No |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the return shape '{ found, record }', which is not in the annotations, and clarifies the key field. This adds useful behavioral context beyond what annotations provide.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is two short sentences, front-loaded with the action and includes the return shape. Every word is necessary; no fluff or redundancy.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple read tool with annotations covering safety and a schema documenting the required key, the description is mostly complete. It explains the return shape and key field. The only gap is the optional 'fields' parameter, which is not mentioned, but that is a minor omission for the core use case.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is only 50%: the 'key' parameter has a description, but 'fields' has none. The tool description does not mention 'fields' at all, so an agent using this description alone would not know that field selection is possible. The description adds no meaning beyond the schema's existing key description, so it fails to compensate for the missing field documentation.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses the verb 'Fetch' with a specific resource 'a single record' and identifies the key field ('id'), distinguishing it from siblings like catalog_query for multiple records or catalog_count_by for counting. This makes the tool's purpose unambiguous.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description clearly states the intended use case: fetching one record by its key. It does not explicitly mention alternative tools or when not to use it, but the context is clear enough to infer. No exclusions are given, so a 4 is appropriate.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.