List the catalog's keywords

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

Annotations only declare readOnlyHint=true; the description adds substantive behavioral context beyond that: the result is vocabulary only with no counts, it mixes user-typed and object-detection-generated keywords, and it can contain terms (e.g. 'zebra', 'toaster') that appear nowhere in the footage. This tells the agent exactly what the output can and cannot be trusted to mean.

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?

Four sentences, front-loaded with the catalog-wide scope before the caveats, and every sentence carries information. Slightly long: the closing 'search for it' advice restates the earlier 'not in the catalog returns nothing' warning, so there is minor 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?

With no output schema, the description does the work of explaining what comes back (a vocabulary list, no counts, mixed provenance). For a single optional-parameter, read-only listing tool, nothing an agent needs to call it correctly or interpret the result is missing.

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 100%, so the 'videos'/'scenes' scope values are already documented, giving a baseline of 3. The description adds a genuinely non-obvious semantic point — that both scopes can contain either user-typed or auto-detected keywords — which clarifies the parameter's meaning beyond the schema text.

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?

States a specific verb and resource ('List every keyword that exists in the whole Fast Video Cataloger catalog') and immediately scopes it against the per-video alternative ('rather than the keywords on one video'). An agent can distinguish this from sibling keyword tools like get_video_tags without opening any schema.

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?

Gives explicit when-to-use context ('find out what you can actually search for before guessing') and a when-not-to-trust-this signal ('a keyword that is not in the catalog simply returns nothing'), plus a redirect ('To find out whether a keyword is really used, search for it'). The alternative is described by behavior rather than named as a specific sibling tool, so it falls just short of the top tier.

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