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

Annotations already cover read-only and open-world nature, and the description adds real context beyond them: the per-call credit cost and the fact that only the public profile surface is returned (exact counts, join date, verified badge). It stops short of covering cache behavior, auth, or what happens for private/suspended accounts.

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?

Two short sentences, front-loaded with purpose followed by the returned fields, with the credit cost as a trailing note. No filler.

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 no output schema, the enumerated field list does the job of telling an agent what it gets back, and the credit cost sets expectations for call volume. The remaining hole is the undocumented cache_max_age parameter and failure modes for non-public accounts.

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% and the description says nothing about either parameter. The handle format is documented in the schema itself, but cache_max_age has no description in the schema and no mention here, so the description does not compensate for the gap.

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 resource and scope ('public profile for an X account') and enumerates the exact fields returned — bio, location, avatar, banner, website, exact follower/following/post counts, join date, verified badge. That field list distinguishes it from siblings like twitter_userTweets or twitter_tweet without naming them, though no alternative is named explicitly.

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 only implied: the field list tells an agent this is the tool for account metadata rather than posts, and 'Costs 1 credit' hints at a paid call to weigh. There is no explicit when-to-use/when-not statement and no reference to sibling tools such as twitter_userTweets.

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