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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint, and openWorldHint. The description adds value by stating the returned fields (AphiaID, accepted name, authority, taxonomic status, habitat flags) and mentioning fuzzy matching and marine-only restriction. It does not contradict the annotations and provides behavioral context beyond what the annotations carry, though it doesn't discuss pagination or rate limits.

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 concise (four sentences) and front-loaded with the core purpose, followed by return values, usage guidance, and source attribution. Every sentence adds value, and it is well-structured for quick parsing by 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 has an output schema that defines return fields, so the description does not need to elaborate on return formats. It explains how to use results with sibling tools, mentions the source and license, and covers the main options (fuzzy match, marine-only). For a search tool, this is complete and leaves no critical gaps.

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%, with each parameter (name, like, offset, marine_only) having a description. The tool description adds little beyond the schema: it mentions fuzzy matching and marine-only restriction, but these are already explained in the parameter descriptions. With full schema coverage, the baseline of 3 is appropriate, as the description does not provide additional parameter-level insight.

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 a specific verb ('Search') and a specific resource (240K+ accepted marine species in WoRMS), and it distinguishes itself from sibling tools by explaining it returns AphiaID and lists downstream tools that use that ID. This makes it easy for an agent to understand what this tool does and how it relates to worms.species.details, classification, and vernaculars.

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 explicitly tells the agent to use the AphiaID from results with worms.species.details, worms.species.classification, or worms.species.vernaculars, which directly guides when to use this tool versus its siblings. It also notes optional restriction to marine-only taxa and fuzzy matching, giving clear context on when to apply those options.

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