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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely new context: no API key is required, and the response includes a built_in flag telling built-in from community species. Return shape and pagination are not discussed, but this is a single-object read.

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 the endpoint mapping and the core capability. The API path mapping is mildly redundant but useful; nothing else is filler.

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 one-parameter read-only lookup with a full annotation set and no output schema, the description supplies the missing context: no auth needed, slug varieties, and the built_in discriminator. Only the return format is unaddressed, which is acceptable given no output schema exists.

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 the single slug parameter is already documented in the schema, so the baseline of 3 applies. The description reinforces that slugs span built-in and community forms and are adoptable, but adds no syntax or format detail beyond the schema.

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 verb-and-resource ('Full profile of any species') and scopes it to a single slug taken from GET /api/house/species/{slug}. The mention that slugs may be built-in or community, with built_in distinguishing them, differentiates it from the sibling list_species.

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?

'Any slug here can be adopted' implies this is the lookup step before adoption, and 'No key needed' signals it is callable without auth, but there is no explicit when-to-use/when-not or named alternative to list_species. Usage is implied rather than specified.

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