get_user_profile

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

No annotations exist, so the description must carry transparency. It indicates 'look up' and lists returned data, implying a read-only operation, but does not explicitly state lack of side effects, rate limits, or error behavior. This is acceptable but not thorough for a tool with no 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 description is two concise sentences, covering the action and the return content without any superfluous words. It is well-structured and easy to parse, making it efficient for an agent.

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?

The tool is simple with one parameter and no output schema. The description mentions the key return fields (name, bio, follower/following counts, tweet count), which provides sufficient context. It does not cover edge cases or error conditions, but for a straightforward lookup, this is adequate. Slight deduction for not mentioning potential limitations.

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?

The single parameter 'username' is fully described with format guidance ('without the @ sign') and an example, which adds meaningful context beyond the schema. The description also reinforces the parameter's purpose by referencing 'by their username'. Coverage is 100% and the added detail is valuable.

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 clearly states the tool's function: looking up a Twitter user's profile by username. It distinguishes from sibling tools like get_my_profile (which targets the authenticated user) and other retrieval methods, using the specific verb 'look up' and resource 'profile'.

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 implies when to use it (for any user's profile via username) and implicitly contrasts with get_my_profile, but it does not explicitly exclude cases or mention alternatives. It provides clear context but lacks direct guidance on when not to use it.

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