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

With no annotations, the description carries the full burden, and it discloses almost nothing: no note that this is a read-only lookup, no behavior when the permit number is unknown, and no permission requirements. The read-only nature is inferable from "One building permit" but never stated.

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 front-loaded sentence-fragment with no wasted words. It is arguably too terse given what is left unsaid, but there is no padding or 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?

The tool is simple (two required params, no nested objects, no output schema), so a short description is defensible. However, with zero annotation and zero schema-description coverage, the description leaves the lookup key semantics and failure behavior entirely undocumented.

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 0%, so the description must compensate. "By its city permit number" loosely maps to the two parameters (city and permit_id) but adds no format, naming convention, or expected value detail beyond what the bare schema fields already list.

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?

"One building permit by its city permit number" identifies the resource (a single building permit) and the lookup key, distinguishing it from the plural siblings (recent_permits, permits_at_address, list_cities). The verb is only implied by the sentence fragment, but the singular lookup is unambiguous.

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?

There is no statement of when to use this versus permits_at_address or recent_permits. The lookup key implies the precondition (you must know city + permit number), but the agent gets no explicit routing guidance or exclusions.

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