user_profile

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

Annotations already declare readOnlyHint=true, and the description reinforces this with 'Read'. It adds valuable behavior beyond annotations by specifying the return format ('clean markdown') and the parameter flexibility (with or without @). This is more than the baseline requirement given the existing 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?

Two short sentences, front-loaded with the core purpose, no wasted words. Every phrase adds value, including the return format and handle guidance.

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?

Given the tool has only one parameter, clear annotations, an output schema, and a low complexity, the description fully covers the essentials: what it does, how to provide input, and what format to expect. No critical gaps remain.

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 schema has 0% description coverage, so the description must compensate. It does so by clarifying that 'username' means the X handle and that it may include a leading @. Though brief, this fully covers the single parameter's meaning and format.

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 ('Read') and resource ('X user's profile'), and distinguishes this tool from siblings like read_tweet and user_timeline by focusing specifically on the profile rather than posts or timelines. The handle-based identifier is clearly specified.

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 makes the usage context clear: you use this tool when you need a user's profile by handle. It also provides input formatting guidance (optional leading @). It does not explicitly name alternatives or exclusions, but the context is unambiguous enough for an AI agent to select correctly.

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