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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is fully covered by structured data. The description adds the lookup-by-id-or-name behavior, but its enumeration of return fields (id, name, description, preview link) duplicates what the existing output schema already provides. With annotations doing the heavy lifting, this is adequate but adds little beyond structured fields.

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 tight sentences: intent first, then behavior, then the negative routing. Every sentence earns its place, though the return-field enumeration partially duplicates the output schema.

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 single-parameter read-only lookup with an output schema, the description covers intent, filtering behavior and alternative tools. Return values need not be explained since the output schema exists, so nothing critical 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% and there is a single optional parameter already documented as 'Ids or names to look up. Default all.' The description's 'Pass styles to look up particular ones' restates the same filtering semantics without adding format, matching rules, or error behavior. Baseline 3 is correct when the schema carries the parameter meaning.

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 caption styles') and immediately frames the user intent it serves ('which caption looks they can choose from'). It also names the siblings it is not (restyle_clip, make_clips), so an agent can separate it from nearby tools 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?

Explicitly states when to use it (user wants to know available caption looks) and when not to (changing a clip), routing to two named alternatives. Nothing is left to inference.

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