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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false. The description adds important behavioral details: cost per ID (0.02 credit), cache behavior relative to get_followers, and that a 403 is free. These go beyond the annotations and help the agent anticipate costs and error handling.

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 concise: four short sentences each carrying distinct information (purpose, cost, cache behavior, error cost). It is front-loaded with the core purpose and contains no filler. Every sentence earns its place.

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 tool with 4 parameters and no output schema, the description covers purpose, cost, caching, and error handling. It does not explicitly describe the response format (though 'numeric ids' implies a list), but the schema documents cursor and count constraints. It is sufficiently complete for an agent to call correctly.

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 75% (user, fresh, cursor have descriptions; count does not). The tool description does not add any parameter-specific guidance. Since the schema already documents most parameters, the description adds no extra value, so it stays at the baseline of 3.

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?

Description clearly states it returns numeric IDs of followers and explicitly distinguishes from get_followers by saying 'no profiles'. It names the resource (follower ids) and the verb (get), making its purpose unambiguous.

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?

It gives a specific usage context by noting it shares the same page as get_followers and that a page read there is a cache hit, implying it's cheaper after fetching profiles. It also implies 'no profiles' as a reason to choose this tool when profiles aren't needed. It lacks an explicit 'use instead of X when...' statement but provides clear context.

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