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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds genuine domain behavior beyond that: bands are year-specific and shift over time, which warns an agent that results are not stable across years and that a stale or omitted year changes the answer. It does not discuss caching or data provenance, but for a read-only reference lookup that is a minor gap.

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 short sentences, front-loaded with the returned content and followed by the one caveat that affects correct invocation. Nothing is repeated from the schema or annotations, and no sentence could be removed without losing information.

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?

An output schema exists, so the description needn't explain return shape, and it correctly focuses on the year-sensitivity caveat instead. With one optional parameter and full schema coverage, the definition is nearly complete; only an explicit statement of when to reach for this tool rather than a sibling 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?

Schema coverage is 100% and the single 'year' parameter is already documented with its default to the most recent session, so the baseline would be 3. The description earns an extra point by explaining why the parameter matters — band definitions are year-dependent, so the year is not optional context but the axis that determines the returned mapping.

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 the resource (the grade key) and enumerates what it returns: what each grade means, the percentage band it covered, and how many legislators received it. An agent can immediately tell this apart from legislator_record, legislator_votes, and legislators_for_town. The only weakness is the absence of an explicit verb, but the content is specific enough that intent is unambiguous.

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?

Usage is implied rather than stated: an agent infers this is the tool to call when it needs to interpret a letter grade or check band thresholds. The sentence 'The bands change from year to year' implicitly argues for passing a year rather than assuming current definitions. However, there is no explicit guidance on when to call this versus the sibling tools, nor any stated prerequisite.

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