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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds value by specifying the exact output content (states/counties and parcel counts) and the evolving nature of coverage, which is useful behavioral context beyond 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?

The description is two sentences with no filler. The primary output is stated first, and the dynamic coverage note provides important context without bloating the definition.

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 parameterless metadata tool with annotations covering safety and openness, this description is complete. It tells the agent what the tool returns and that the result may change over time, which is all an agent needs to decide whether to call it.

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?

The tool has zero parameters and 100% schema description coverage, so the schema is trivially complete. The description appropriately focuses on what the tool returns rather than parameter details, matching the baseline for parameterless tools.

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 uses a specific verb ('List') and resource ('states/counties the parcel tools currently cover' with parcel counts), which clearly identifies what the tool does. It is easily distinguished from sibling tools like parcel_search or parcel_details, which operate on individual parcels rather than describing coverage.

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 clearly implies this tool is for checking current coverage and parcel counts, and the note that coverage grows by state over time signals that this is a dynamic, approximate-status tool. It does not explicitly name alternatives or exclusion conditions, but the context is sufficient for an agent deciding between this and parcel data lookups.

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