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

Annotations already establish the read-only/idempotent safety profile, so the description's job is to add characterization. It does: it warns that the endpoint does not publish reported count fields, so counts are null rather than back-calculated, and that offenses cover only those known to law enforcement. This is valuable data-quality 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?

Three sentences, front-loaded with the capability, then usage examples, then the data caveat. Dense but each sentence earns its place; no filler or repetition of the title.

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 carries the burden of explaining returns, and it does so by stating counts come back null and describing the reporting-population/coverage fields. For a six-parameter read-only tool this is complete enough to call correctly.

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 description coverage is 100%, so all six parameters are already documented in the schema. The description adds little parameter-level meaning beyond 'bounded' (implying limit/offset pagination) and the offense-rate framing; baseline 3 is appropriate.

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 ('Return') and resource ('U.S. monthly FBI summarized UCR offense-rate trend with national reporting population and coverage'), and the national scope implicitly separates it from the state-level fbi_cde_* siblings. An agent can distinguish it without opening the schema.

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 concrete use cases ('national burglary rate trend in 2020', 'U.S. violent-crime reporting coverage by month') and a positioning hint ('national context before a state comparison'). It stops short of explicitly naming the alternative tools (e.g. fbi_cde_state_crime_trend), so it is clear context without full routing.

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