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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds the API-key prerequisite and confirms the payload is a small vocabulary list, but that key requirement is largely restated from the `_apiKey` schema description, so added behavioral value is modest.

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 short sentences, front-loaded with purpose, then the routing guidance, then the prerequisite and a concrete call example. Nothing is wasted even though the API-key note partly duplicates the schema.

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 read-only, small, parameterless-by-nature vocabulary endpoint with no output schema, the description conveys what the data contains, why it matters and how to authenticate. Nothing needed to invoke it correctly 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%, with page, limit and _apiKey all documented inline, including limits and default. The description only references `_apiKey`, so it adds nothing beyond the schema and the baseline 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?

States a specific resource (the species vocabulary RescueGroups uses) and describes its content shape: singular, plural and young-animal words per species. It also differentiates itself from the sibling rescuegroups_adoptable by framing itself as the source of that tool's `species` value.

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?

Explicitly tells the agent to use it 'to get the exact `species` value rescuegroups_adoptable expects', which gives a clear use context and names the sibling. It does not state when-not to use it or any alternative lookup path, which keeps it below a 5.

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