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

Annotations cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower; the description still adds real value by disclosing ordering ('nearest first') and the returned fields (address, phone, website, adoptable-pets page, hours, directions, source, licence). It doesn't mention pagination or how many results come back by default, but the return-shape disclosure is unusually concrete for a tool with no output schema.

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?

Two sentences, front-loaded with the resource and locator formats, then the routing hint. The field list is dense but each item earns its place; only the trailing 'source and licence' pairing reads as 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?

With no output schema, the description sensibly enumerates return fields and input formats, and gives a usage trigger for a 5-parameter tool. It is slightly incomplete in not clarifying that all parameters are optional (0 required) or how the defaults for limit/radius_miles behave.

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 only 20%, so the description must carry the load; it explains the accepted locator formats (US ZIP, 'town, ST', or lat,lon), which maps onto near/lat/lon. However limit and radius_miles are undocumented in both the schema and the description, leaving half the parameters opaque.

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 ('shelters and rescues near...') and a distinctive scope ('that are not on Petnecto yet'), which separates it from find_pets and get_rescue. An agent knows exactly what this returns without opening the schema.

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?

Gives an explicit trigger tied to a named sibling: 'Use it when find_pets finds nothing near the person.' Clear context and an alternative, though it doesn't state when NOT to use it (e.g. when find_pets does return results).

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