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

Annotations already declare the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower. The description adds genuine behavioral context beyond those: counts are null rather than back-calculated, and the data reflects 'crimes known to law enforcement only' — an important semantic caveat about the returned values.

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, each doing distinct work: purpose/scope, usage examples, then a data caveat. Front-loaded with the core definition. Slightly dense but nothing is wasted.

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?

There is no output schema, so the description carries the burden of explaining returns; it does so conceptually (monthly offense-rate trend plus national reporting population and coverage) and flags the null-count behavior. Combined with 100% parameter coverage, an agent has enough to call and interpret it, though pagination semantics for limit/offset are left to the schema.

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 every parameter (including the enum constraints on offense and response_format) is already documented in the schema. The description adds only the general notion of a 'bounded' trend, which does not materially extend the parameter definitions. 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 and resource ('Return a bounded U.S. monthly FBI summarized UCR offense-rate trend with national reporting population and coverage') and pins the scope as national and monthly. This distinguishes it from the state-level siblings (fbi_cde_state_crime_trend, fbi_cde_state_month_snapshot) without requiring the schema to be opened.

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?

Provides concrete trigger examples ('national burglary rate trend in 2020', 'U.S. violent-crime reporting coverage by month') and a positioning cue ('national context before a state comparison'), which implies fbi_cde_compare_state_to_national. It stops short of naming the alternative sibling explicitly, so it is clear context rather than full when/when-not routing.

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