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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered. The description adds genuinely non-structured context — the call is free and requires no API key — and discloses the shape of the returned data (plan fields, per-lookup credit costs, extract download pricing), which goes 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?

Two sentences, tightly packed with useful facts, and front-loaded with the highest-value qualifier ('Free, no API key'). Every clause earns its place by naming a returned data category or an out-of-scope case.

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?

With no input parameters and no output schema, the description carries the burden of describing return values and it largely does so, listing plans, credit costs and extract downloads by field. It could be slightly firmer about the response structure or ordering, but nothing an agent needs in order to call it is missing.

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 takes zero parameters, so there is no parameter semantics to explain and the baseline of 4 applies. The description correctly does not invent or discuss any inputs.

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 states a specific verb and resource ('Returns the monthly API plans...') and enumerates exactly what is returned: price, included credits, overage per credit, rate limit, plus per-lookup credit costs and one-off extract downloads. This is unmistakably distinct from the geo-lookup siblings like find_parcels_by_apn or check_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 establishes the context of use: it is free, needs no API key, and explicitly routes statewide/nationwide licence questions to an external pricing page rather than this tool. It does not spell out an explicit trigger (e.g. 'call this before estimating credit spend'), so it stops short of full when/when-not guidance.

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