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

Annotations already declare read-only, non-destructive, idempotent behavior. The description adds value by specifying the return content in detail (file URLs at all resolutions, duration, dimensions, attribution), which goes beyond the annotations and clarifies what the agent should expect from the response.

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?

The description is a single well-structured sentence, front-loaded with the action and resource. Every phrase earns its place, listing both the input context and key output fields without 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 an output schema present and comprehensive annotations, the description provides all necessary context: the input, the output highlights, and the resource scope. It fully equips the agent to select and invoke the tool correctly for single-video metadata retrieval.

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 schema only defines 'id' as a number. The description enriches this by clarifying that the id is a Pexels video ID and that the tool returns a single video. This compensates for the low schema coverage by tying the parameter to the resource being fetched.

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 uses a specific verb ('Fetch') and resource ('full metadata for a single Pexels video'), clearly distinguishing this from sibling tools like video_search and video_popular. It lists the exact data returned (file URLs, duration, width, height, attribution), leaving no ambiguity about the tool's function.

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?

The phrase 'by numeric id' makes clear this tool is for retrieving a single known video, contrasting with search/popular siblings. However, it does not explicitly state when not to use it or name alternative tools, so it falls short of full exclusion guidance.

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