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

Beyond readOnlyHint/openWorldHint, the description discloses concrete behavior: view/like/comment counts are always null on Mashable, `mediaUrls` is empty when an older video's file is gone, and the call is free in that case versus normally costing 1 credit. Cost and degraded-result behavior are exactly the kind of context annotations cannot carry. It does not cover rate limits or authentication, keeping it short of a 5.

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 compact sentences, front-loaded with the resource and then the returned fields, then edge cases and cost. The opening 'Video details.' largely restates the title, which is the only wasted fragment; everything after it carries distinct information.

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?

There is no output schema, so the description must describe the return payload itself – and it does, enumerating the fields and the ordering of video file URLs. Combined with the null-field and empty-`mediaUrls` caveats and the credit cost, an agent knows what it will get and what anomalies to expect.

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 50%: the `url` parameter is well documented in the schema (mashable.com/video/… URL or slug), but `cache_max_age` is undocumented in both schema and description. The description adds no parameter-level meaning, so the baseline of 3 applies with an unresolved gap on the second parameter.

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 names a specific resource and scope: 'A Mashable video: title, summary, author, tags, duration, thumbnail and the addresses of its video files.' Combined with the platform-specific tool name, an agent can tell it apart from the many other *_video siblings (youtube_video, vimeo_video, etc.) without opening the 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?

Usage is implied rather than stated – fetch a single Mashable video by URL/slug. There are no siblings for the same platform to disambiguate against and no explicit when-not guidance, though the note about older videos with dead files hints at a failure mode worth knowing before calling.

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