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

With no annotations, the description carries the burden and it delivers meaningful behavioral detail: 1-credit cost, no charge for empty results/failures, and cache behavior with a free 24h hit when cache=true. It does not describe what metrics are included or any rate limits, which keeps it from 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?

The description is short and front-loaded with the core purpose. It loses a point because 'Costs 1 credit' repeats the parenthetical '(1 credit)' in the first sentence.

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 two-parameter tool with no output schema, it covers cost, caching, and platform scope, but 'unified metrics' does not say what metrics are actually returned. An agent can invoke it correctly but may not know whether the response satisfies a request for specific data.

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 both url and cache are already fully documented, so the description adds only cost/cache context rather than parameter meaning. Baseline 3 is appropriate.

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 and resource: returns unified metrics for a single post, video, or reel, with platform auto-detection. The schema's 'unlike single-platform endpoints' explicitly distinguishes it from the many platform-specific detail tools in the sibling list.

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 plus schema gives a clear use case: cross-platform URLs expected for unified metrics, as opposed to single-platform endpoints. It does not explicitly rule out alternatives like analytics_compare or platform-specific deep-dive tools, so it stops short of a full when/when-not decision rule.

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