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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful output-scope context: it retrieves one species and includes full details such as every common name, country observation counts, full photo credit, and Wikipedia summary.

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 with no filler. The core operation and target resource are front-loaded, and the field enumeration is compact but meaningful.

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 a rich output schema, full schema coverage for both parameters, and annotations covering safety and idempotency, the description is complete enough for an agent to invoke the tool correctly. The reference to a species slug and the one-species scope fill the remaining contextual need.

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%: both 'id' (with slug format and example) and 'lang' (with enum and default) are fully documented. The description adds no parameter-level semantics beyond naming the resource, which is acceptable because the schema already carries the burden.

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 uses a specific verb ('Read') and a specific resource ('one species'), then enumerates the exact fields returned. It clearly distinguishes this tool from sibling list/search tools by emphasizing retrieval of a single species by slug.

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 makes clear this is for reading a single species' full record, which implies it should be used after search_animals and not for listing or searching. It does not explicitly name alternatives or exclusion conditions, but the sibling set and schema reference to search_animals make the usage context clear.

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