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

Annotations give little safety context (readOnlyHint false, destructiveHint false). The description adds important behavioral detail: output is always JPEGs in a ZIP and there is no PNG option despite the tool blurb. Side effects or file handling details are not covered, but the key output contract is disclosed.

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 one compact, front-loaded sentence that conveys the action, resource, frame rate behavior, and output format. It also includes a useful correction about JPEG-only output. No wasted words.

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 simple extraction tool with no output schema, the description supplies the missing return-format contract (ZIP of JPEGs) and clarifies the output type. Parameter constraints are covered by the schema. It does not mention supported video formats or potential processing time, but that is a minor gap given the tool's simplicity.

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 all three parameters have meaningful schema descriptions. The tool description does not add parameter-level semantics beyond what the schema already provides, 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?

The description states a specific verb and resource: 'Extract frames from a video at a specified frame rate as JPEG images (returned as a ZIP).' This clearly differentiates it from siblings like media_extract_audio and media_trim_video.

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 description implies when to use it—when you need JPEG frames from a video—but it does not explicitly name alternatives or give when-not-to-use guidance. Context is clear, but exclusion guidance is missing.

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