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

Annotations already declare read-only, idempotent, non-destructive, closed-world, but the description adds behavior they cannot: results are newest-first, results carry a 'state' field while a file is not ready, and the tool functions regardless of open-project state. That is exactly the extra context annotations cannot supply.

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?

Front-loaded with purpose, then routing, then result shape in a compact paragraph where nearly every clause carries new routing or contract information. The result-field enumeration is slightly heavy, but it substitutes for a missing output schema, so it earns its place.

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 supplies the return contract (Library id, name, kind, durationSeconds, width, height, createdAt, usedIn, state) and the follow-up path (add_from_library using those ids). Combined with full parameter coverage and clear sibling routing, nothing an agent needs to call it correctly 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 description coverage is 100%, so kind, limit and query are already fully documented, including the null semantics. The description restates that query matches words in file names, adding no syntax or format meaning beyond the schema, so baseline 3 applies.

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+resource+scope: search the user's Library across all projects and the Library page, newest first. It explicitly contrasts itself with search_assets ('lists only the project's media'), so an agent can separate the two without opening either 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 an explicit trigger ('when the user means their own footage, photos or sounds that are not in the open project') plus named alternatives for adjacent needs: search_video_moments for visual/audible content and read_video_intelligence for indexing progress. It even notes it works with or without an open project, removing the main precondition ambiguity.

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