Catalog size

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The readOnlyHint annotation already covers the safety profile, and the description adds real context beyond it: the counts come from the user's local video library and explicitly not from cloud storage or the file system, and the call doubles as a connectivity check. It does not describe the response shape or any cost of a large catalog, which keeps it out of the top band.

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?

Three short sentences, each earning its place: what is counted, what scope it covers, and when to call it. The payload (counts) is front-loaded and nothing is repeated from the schema or annotations.

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 zero-parameter read-only stats tool with no output schema, the description covers what is counted and the data scope, which is enough for correct invocation. It leaves the exact return field names and any error/empty-catalog behavior unstated, a minor gap given the tool's simplicity.

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?

The tool takes zero parameters, so there is no parameter semantics for the description to add; the baseline for a no-arg tool is 4. The description correctly implies the call is global with no filtering options.

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 names the exact resource (the Fast Video Cataloger catalog) and the exact quantities returned (counts of videos, actors and images), which is a specific verb+resource statement rather than a restatement of the title. It is immediately distinguishable from siblings like search_videos or get_video, which return entities rather than aggregate counts.

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?

It gives explicit usage context: "Useful as a first call to confirm the connection works and to judge how broad a search should be." That tells the agent when to call it (startup, sizing a search) but names no alternative tool or exclusion, so it stops short of a full when/when-not comparison.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.