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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the description's real contribution is the tiering model: base responses carry name, FIPS and GEOID, while border polygons and land area require a paid plan, and each call costs 10 credits. That is concrete operational context an agent cannot get from the schema. It stops short of 5 because it doesn't say what happens on an invalid or unrecognized code.

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 compact sentences with the resource identified first and the tier/cost caveat last. The opening 'State Boundaries: State Boundaries provides' duplicates the name and title, which is the only wasted wording.

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 one-parameter lookup with an output schema and full annotation coverage, the description supplies everything essential, including the free-versus-paid field split that the output schema cannot convey. It is only marginally incomplete regarding invalid-input behavior.

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% and the single parameter already documents the two-letter code with an example, so the description merely restates the same format. Baseline 3 applies since the schema does the heavy lifting and the description adds no new constraint such as case sensitivity or territory handling.

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 specific resource (US state boundaries with Census identifiers) and the exact input form (two-letter postal code), so an agent can tell this apart from adjacent tools like CountryBoundaries or CountyDataLookup at a glance. It falls short of 5 because it never explicitly contrasts itself with those siblings.

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?

There is no when-to-use or when-not-to-use guidance: nothing tells the agent to prefer CountyDataLookup for sub-state data, CountryBoundaries for national outlines, or what to do if it only has a state name rather than a code. Usage is only inferable from the mention of the two-letter postal code input.

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