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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so the safety profile is covered. The description adds genuinely useful behavioral context by enumerating the response contents (location, adoption page, contact details) — notable since there is no output schema. Minor gap: no note on behavior for an unknown id.

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?

A single tight sentence that front-loads the verb+resource and then the payoff (what fields come back). No filler, no redundancy.

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 lookup with no output schema, the description is nearly sufficient: it explains what is returned and where the input id comes from. It could say slightly more about behavior on an unmatched or malformed id, but nothing essential is absent.

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?

With schema coverage at 0%, the description carries the burden, and it does add real meaning: it tells the agent the id originates from a pet's 'rescue.id', which is not encoded anywhere in the schema. It doesn't restate the accepted id patterns, but the provenance is the more valuable missing piece.

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+resource ('One rescue or shelter by id') plus the key fields returned (location, adoption page, email, phone), so an agent knows exactly what this returns. It distinguishes itself from find_shelters_near by the 'by id' lookup, though it doesn't name that sibling 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 parenthetical '(from a pet's rescue.id)' implies when to reach for it — after get_pet surfaces a rescue id — but there's no explicit when/when-not statement or named alternative to find_shelters_near. Usage is inferable rather than stated.

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