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

With no annotations, the description carries the transparency burden. It discloses meaningful grouping behavior ('Cities are grouped by metro area') and gives a concrete example of metro coverage (Minneapolis/St. Paul suburbs). It doesn't mention return format, pagination, or error behavior, but for a simple listing tool, this is reasonably transparent.

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?

The description is three sentences, all of which serve a purpose: stating the function, giving usage guidance, and explaining a key behavioral detail. It is front-loaded with the verb and resource, and there is no redundant filler.

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 with two parameters, one required, and full schema coverage. The description covers purpose, when to use it, and grouping behavior. It doesn't describe the return value structure, but the lack of an output schema is somewhat mitigated by the clarity of the listing behavior. Slightly more detail on what the output looks like would push it to 5.

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 100%, with parameter descriptions already explaining 'niche_id' and 'state.' The description adds context about metro-area grouping and the 'minneapolis-mn' slug format, but this is more about output behavior than parameter semantics. It repeats the optionality of state already implied by the schema, so it doesn't significantly elevate beyond the baseline.

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 clearly states a specific action ('List') and a specific resource ('available cities and metro areas where verified providers operate'), scoped by 'for a given niche.' It distinguishes itself from sibling tools like list_niches and search_providers by specifying its role in discovering city slugs.

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 description explicitly says 'Use this to discover valid city slugs before calling search_providers,' providing clear when-to-use guidance and naming the downstream tool. It also notes the optional state filter, which helps the agent decide how to invoke it.

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