Get X User Profile

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds the specific return fields, which is useful but not a distinct behavioral trait beyond what annotations communicate. No additional side effects, rate limits, or auth requirements are disclosed.

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?

A single sentence of 17 words, front-loaded with the action verb 'Fetch.' It efficiently covers purpose, scope, and return fields with zero waste. Every word contributes meaning.

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 read-only profile fetcher with 2 well-schema'd parameters and no output schema, the description tells the agent exactly what the tool does and what it returns. The annotations cover safety. No significant gaps in guidance for this simple tool.

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 100% – both parameters (username and response_format) have descriptions in the schema. The description itself adds no parameter-level detail, so baseline 3 applies. The schema already documents the username pattern, max length, and response format enum.

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 'Fetch an X user profile by username' – a specific verb, resource, and identification method. It lists the returned fields (bio, follower/following counts, post count, creation date), and the username-based identification distinguishes it from siblings like x_get_my_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 provides clear context: use this when you have a username for an X profile. It does not name alternatives or exclusions, but the 'by username' phrasing implies the appropriate scenario. Sibling x_get_my_profile exists, but the tool description itself is unambiguous about when it applies.

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