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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds real behavioral content on top: output is a county list with per-county counts, only counties that actually have providers are included, and the category filter is optional. Remaining gaps like ordering or how zero-count counties behave are minor given the annotations.

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 sentence with the scope constraint ('For one state') front-loaded and no redundant restatement of the tool name. The phrasing is slightly compressed/awkward ('For one state, the counties that...') but every clause carries information.

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 tool with an output-less schema, the description does describe the return payload (counties plus counts), which is the important part. It stops short of covering the category parameter's semantics, result ordering, or behavior for a state with no matching providers, leaving a few gaps an agent would want.

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%: 'state' is documented (two-letter code) but 'category' has only an enum and no prose. The description does add meaning by clarifying category is optional and narrows the counts, but it doesn't explain the category semantics or confirm that omitting it aggregates across all categories. Baseline 3 given the schema carries part of the load.

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 names a concrete resource (counties) and the payload (each county plus its provider count), scoped to 'one state' and optionally one category. That is far more specific than the bare tool name, though it never explicitly contrasts itself with siblings homeless_states or homeless_providers_search, so an agent must infer the boundary.

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?

Usage is implied rather than stated: 'the counties that have providers' signals this is a coverage/aggregation lookup, and 'optionally for one category' signals an optional narrowing filter. There is no explicit when-to-use versus the sibling search tool, and no note about what happens outside the listed states.

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