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

Annotations already cover the safe read-only, idempotent profile. The description adds valuable behavioral context by disclosing exactly what the record contains, including the synonym-resolution semantics (unaccepted status and valid_AphiaID) and the data source/license. 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?

The description is well-structured and efficient: a front-loaded purpose sentence, a field-list sentence, a concrete usage directive, and a brief source note. Every sentence earns its place without padding or repetition.

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 single-parameter lookup tool with an output schema, the description is complete: it explains what is returned, when to use it, how synonym chains resolve, and even the data license. No critical behavioral or selection context is missing.

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 description coverage is 100% and already fully documents aphia_id with type, constraints, an example, and guidance to obtain the ID via worms.species.search. The description adds no new parameter-specific meaning beyond restating 'by its AphiaID,' so the baseline of 3 is appropriate.

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 and resource: 'Retrieve the full WoRMS Aphia record for a taxon by its AphiaID,' and enumerates the returned content (taxonomy, accepted name, valid AphiaID, citation, LSID, habitat flags, last-modified). It implicitly differentiates from sibling search/classification tools via the 'use this to resolve synonym chains' use case, but does not explicitly name sibling alternatives.

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 gives a clear when-to-use directive: 'Use this to resolve synonym chains — if status is "unaccepted", valid_AphiaID points to the accepted taxon.' This provides concrete context for selecting this tool. However, it does not mention exclusions or name alternative sibling tools (e.g., search or classification), so it stops short of full guidance.

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