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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), so the bar is lower. The description still adds real value: it discloses the payload contents (photos, stated facts, adoption fee, shelter contact) and the disambiguation behavior — 'Lists choices when an ID is shared' — which is a behavioral trait not captured anywhere in the structured fields.

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?

One dense sentence plus a short trailing clause; the identifier forms and the return contents are front-loaded before the edge-case behavior. No filler, though the trailing disambiguation sentence is slightly disjointed from the opener.

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 usefully enumerates what comes back (photos, facts, fee, shelter and contact route), and it flags the ambiguous-ID case. For a simple two-parameter lookup this is essentially complete; only explicit routing guidance to sibling tools 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%, so both parameters are already documented, giving a baseline of 3. The description echoes the three accepted ID forms but adds no syntax, format, or validation nuance beyond what the schema states.

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 — retrieving ONE pet — and enumerates the accepted identifier forms (Petnecto ID, shelter pet ID, PetHarbor URL). The singular scope implicitly separates it from list-oriented siblings like find_pets and show_pets, though 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?

Usage is implied by the identifier-based framing: use this when you already have an ID or URL, rather than searching. However, no explicit when-to-use/when-not statement or named alternative (e.g. find_pets for discovery) is given.

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