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

Annotations already establish readOnlyHint and idempotentHint, so the description's job is to add context. It adds the cost ($0.05 USDC via x402) and the specific return fields, which are concrete and useful. It does not discuss potential errors or rate limits, but the annotations lower the bar; the added value is meaningful.

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 a single, efficient sentence that front-loads the action and immediately lists the included fields and cost. No wasted words or repetition of schema details.

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 description compensates by listing the fields returned. It also covers the cost. It omits error conditions or prerequisites, but for a read-only single-parameter tool, this is largely sufficient. Minor gaps do not hinder correct invocation.

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 fully describes the handle parameter with an example and explanation of the @ prefix. The description adds no further parameter-level detail, so the schema carries the weight. Baseline 3 is appropriate given 100% schema coverage.

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 retrieves a comprehensive profile snapshot for an X handle and enumerates the specific data fields (display name, bio, follower counts, etc.). This distinguishes it from sibling tools like interzoid_x_handle and interzoid_x_last_three_posts, which focus on narrower subsets.

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 use when a full profile is needed ('comprehensive snapshot') but does not explicitly contrast it with the sibling X tools or state when not to use it. No alternative tool names are mentioned, so the agent must infer routing from the field list.

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