Video Metadata

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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds non-obvious operational context: the API-unit cost profile relative to Gemini, which is genuinely useful for tool selection. It does not cover pagination or rate limits, keeping it at 4.

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 purpose sentence followed by return fields and cost. Efficient and well organized; the return-field enumeration is slightly redundant given an output schema exists but is not wasteful.

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 tool with full annotations, a documented output schema, and cost context provided, nothing an agent needs to call it correctly is missing. The description is complete for its complexity.

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% and the single url parameter is fully documented in the schema. The description implies the input is a YouTube video but adds no syntax or format detail beyond the schema, so the 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 (Fetch) and resource (YouTube video metadata) and differentiates from the analysis-oriented sibling by specifying 'without Gemini analysis'. An agent can distinguish this from video_analyze or media_metadata without opening a 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?

'Without Gemini analysis' plus the cost line (1 YouTube API unit, 0 Gemini units) clearly signals the context in which to prefer this over video_analyze. It stops short of an explicit 'use X instead when Y' statement, so it earns a 4 rather than 5.

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