Lookup animal by EID

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, yet the description still adds real behavioral value: it discloses the two failure modes (not-found on no match, ambiguity error on multiple matches) and the Reader permission prerequisite. It does not describe the success payload, but the error semantics are the more valuable disclosure here.

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, no filler, with the read-only scope and farm constraint front-loaded before the edge-case behaviors and the permission requirement. Every sentence carries distinct information.

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 no output schema, the description carries the burden of explaining outcomes, and it does cover the not-found and ambiguity cases plus the auth requirement. The successful return shape is left unstated, which is a minor gap for a read tool.

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 coverage is 100%, so the baseline is 3. The description goes beyond the schema by clarifying that the EID match is exact and that the lookup is confined to one farm, which sharpens the meaning of both the eid and farm_id parameters beyond their terse schema descriptions.

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 with precise scope: read-only, exact EID match, single farm, across inventory statuses. The 'never creates or changes animals' clause implicitly separates it from find_or_create_animal_by_eid, but no sibling is named explicitly.

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 read-only/exact-match framing implies when this tool is appropriate versus the create-capable sibling, and 'Requires Reader access' sets a precondition. However, it never states when to prefer it over find_animal_by_identifier or get_animal, leaving the routing to inference.

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