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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, covering the safety profile. The description adds valuable behavioral context: it specifies the exact output structure (nested hierarchy with AphiaID, rank, scientific name) and the data source/license, which is useful for an agent deciding whether this tool fits.

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?

Three sentences, each earning its place: the first states the action, the second details the output, and the third gives use cases and attribution. No filler or redundancy. The most critical information is front-loaded.

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 simple, single-parameter retrieval tool with complete schema and annotations, the description fully covers what an agent needs: the operation, output structure, and usage context. Nothing essential 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?

The schema describes the only parameter (aphia_id) with type, requirement, and an example. The tool description reinforces that it's by AphiaID but adds little beyond the schema. Since schema coverage is 100%, the description doesn't need to compensate. Baseline 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 ('Get'), a clear resource ('full taxonomic classification tree'), and the key parameter (AphiaID). It distinguishes itself from sibling tools like worms.species.details and worms.species.search by focusing on the hierarchical tree rather than details or search. The use cases (building trees, verifying rank placement) further clarify its niche.

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 states when to use it ('Ideal for building taxonomic trees, verifying rank placement, or navigating the WoRMS backbone'), which provides clear context. It doesn't explicitly mention alternatives or when not to use it, but the specific purpose makes it fairly evident.

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