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

Annotations already carry the full safety profile (readOnly, openWorld, idempotent, non-destructive), so no contradiction exists. The description adds one behavioral detail beyond them — population-descending sort order — which is genuinely useful. However, it does not mention default limit behavior or output shape.

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 with zero filler. The core purpose is front-loaded and the ordering nuance is appended efficiently.

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 simple list-returning tool with strong annotations and no output schema, the description covers purpose and sort order. Gaps remain: limit semantics are left to the schema, state disambiguation is implied, and no mention of result size defaults — but these are minor for a straightforward lookup.

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 only 33% (only 'state' is documented in the schema). The description adds 'US' context and ordering, which weakly relates to state and limit, but it does not explain what 'limit' caps, when 'state' is needed, or how city/state interact for disambiguation. With low coverage, the description under-delivers on compensating for the undocumented parameters.

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?

Description states a specific operation ('All ZIP codes of a US city') with a distinguishing detail ('largest population first'). The verb+resource combination clearly separates it from siblings like nearest_zip, zip_lookup, and zips_in_radius, which are different operations entirely.

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 purpose implies when to use it (listing all ZIPs for a city), and the sibling names make the alternatives evident, but there is no explicit 'use this when / use that instead' guidance or exclusions. An agent must infer the boundary from names alone.

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