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

Goes well beyond the readOnly/idempotent/non-destructive annotations by disclosing the output vocabulary (differs, same, cannot_compare), clarifying that cannot_compare is not a 'no', forbidding fabricated totals/rankings, and warning that quoted text is untrusted data. This is unusually rich behavioral context for a read-only tool.

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?

Front-loads the purpose, then layers output semantics and safety constraints efficiently. Slight redundancy between 'no total, no rank, no winner' and 'do not call any of them strong or weak', but nearly every sentence earns its place.

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 output schema, the description fully carries the burden of explaining return values (per-row differs/same/cannot_compare) and the absence of aggregate scoring, so an agent can interpret results correctly without further docs.

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%, so the codes/names format is already documented. The description still adds value by clarifying the order-sensitivity of the array and that DC is accepted, but it does not add syntax detail beyond the schema.

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?

States a specific verb (compare), resource (US states/DC), arity (two or three), and mode (question by question, in the order given). This clearly separates it from single-entity siblings like get_state or get_country.

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?

Gives strong operating context: the order of inputs matters and the tool is for 2-3 entities at once, which implies the single-state alternative. However it never explicitly names a sibling or states when not to use it, so the routing guidance is inferable rather than spelled out.

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