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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds useful context beyond that: the 1–90 day window bound and the word "Free," which signals no paid tier or quota barrier. It says nothing about the shape of the result (e.g. whether zero-count categories are returned), and there is no output schema to cover that gap.

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 compact sentence with the counted resource, grouping, window, and scope all front-loaded. Every clause carries information; nothing is padded or restated from the title.

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 two-parameter read-only counting tool this covers the essentials, but with no output schema the description should indicate what a result row looks like (category label plus count) or whether an all-areas query returns per-area breakdowns. The unresolved overlap with count_permits also leaves a decision gap.

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 50%: jurisdiction has a description pointing to list_coverage, while days has only structural bounds. The description clarifies "last N days (1-90)" as a lookback window and that area is optional, adding modest meaning, but it does not explain default behavior or how categories are defined.

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?

Specific verb and resource ("count building permits"), with grouping ("by category") and scope ("for one area or all") stated up front. It does not name or distinguish itself from the near-identical sibling count_permits, nor from permit_trends, so an agent cannot fully disambiguate from the text alone.

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?

No statement of when to use this versus count_permits, permit_trends, or search_permits, all of which sound applicable to permit counts. The only routing clue ("Use list_coverage for names") lives in the schema, not the description, and "for one area or all" merely implies the jurisdiction parameter is optional.

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