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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds useful behavior beyond that — results are ordered newest-first, and scope is limited to "supported" cities/counties — but omits pagination/limit behavior and what happens for unsupported locations.

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 compact sentences that are well front-loaded: usage trigger first, return semantics second. Nothing is wasted, though "supported city or county" is slightly vague phrasing that could be tightened.

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 is right to say what it returns, but it doesn't specify the returned fields, the limit default, or behavior for unsupported areas. For a simple 3-parameter lookup this is adequate but leaves gaps an agent may hit at call time.

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 33% (only zip is documented), so the description has to compensate. It clarifies that zip is an optional narrowing filter and that city/county is the primary scope, which helps, but limit (max 50, default unknown) is undocumented in both the schema and the description.

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?

The description states a specific verb and resource ("Returns the newest building permits") plus scope (city/county, optional ZIP). It distinguishes itself implicitly from address- and radius-based siblings via the neighborhood/ZIP framing, but never names an alternative like permits_near, so differentiation is left partly to inference.

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?

"Use when someone asks what is being built in their neighborhood or ZIP code" is a clear, concrete usage trigger. It offers no explicit exclusions or sibling comparisons (e.g., when to prefer permits_near or permits_at_address instead), so it stops short of the top tier.

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