Get User Subscriptions

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

Beyond the annotations (readOnly, idempotent, openWorld, non-destructive), the description discloses the auth requirement (TweetAPI API key), the request cost model (one request per call, usually 1 unit, with a per-result cost estimate), and the page-scoped return shape. These are exactly the operational traits an agent needs and are not derivable from the annotations.

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 definition is dense but front-loaded: identity of the resource first, then the sibling disambiguation, then cost and pagination. A few clauses are packed into one long sentence, which slightly reduces scannability, but virtually every clause carries information an agent would otherwise have to guess.

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 paged, read-only, metered endpoint, the description covers the essentials: what is returned per page, how to continue, what it costs, and what auth is needed. With an output schema present and full schema coverage, the description does not need to enumerate return fields, and it correctly does not.

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 already 100%, so the baseline is 3, but the description adds real meaning by explaining the cursor round-trip ('call again with cursor set to this result's completeness.nextCursor'), which links the input parameter to a specific output field. The username-lookup fallback is left to the schema rather than repeated here, which 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?

The description states a specific verb and resource — fetching one page of accounts a user ID pays to subscribe to — and qualifies it with the concrete subscription types (Premium creator subscriptions, Super Follows). It explicitly distinguishes itself from the nearest siblings by stating 'This is not the following list,' so an agent can separate it from tweetapi_user_following_list and tweetapi_user_following_ids without opening schemas.

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?

Clear routing guidance is present: the negation of the following list tells the agent when not to use this tool, and the description explains that pagination continues by re-calling with the previous result's completeness.nextCursor. The only gap is that it doesn't name the specific sibling tool to use instead when the agent actually wants following data, leaving the agent to infer tweetapi_user_following_list.

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