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

Annotations already declare readOnly and idempotent behavior. The description adds concrete return structure (platform list with exists, url, status_code) and rate limits, providing valuable expectations beyond the schema. No contradictions with 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 compact sentences front-load the core action and scope, then efficiently cover use cases, rate limits, and return shape. Every sentence contributes value with no filler.

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 (one parameter) and the description provides all essential context: platforms checked, use cases, rate limits, and expected output. Even though an output schema exists, the description's return format summary adds clarity without needing more.

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 input schema already fully documents the single parameter (100% coverage) including the '@' prefix rule and examples. The description adds no new parameter-specific details, so the baseline score of 3 applies.

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 opens with a specific verb ('Search') and a clear resource ('username across 15+ social/dev platforms'), listing concrete platform examples. This distinguishes the tool from sibling lookup tools such as domain_report or ip_lookup.

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?

It explicitly states primary use cases ('OSINT investigations and identity verification') and provides rate limits, giving clear context for when to use it. It does not name alternatives, but no sibling tool overlaps in functionality, so exclusions are unnecessary.

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