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

Annotations already establish it as a safe, idempotent, open-world read, and the description adds real context on top: an API key is needed, free results expose only a subset (total, window, coverage state, largest category) while keyed calls return every category, and staleness differs (6 hours vs 15 minutes) so figures can briefly diverge after a publish.

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-loaded with the payload scope before credentials and freshness caveats, and essentially every clause carries information. The sentences are long and comma-heavy, which slightly slows parsing, but little 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?

With an output schema present, the description needn't enumerate return fields, and it still sketches the free-tier payload shape and the freshness caveat. For a one-parameter read tool that is close to complete; only the sibling-routing guidance 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 postcode parameter is fully documented with an example in the schema, so the baseline of 3 applies. The description contributes only the 0.5 km fixed-radius framing, no extra syntax or format guidance 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?

Opens with a specific verb+resource and scope: published street-crime records in a fixed 0.5 km circle around a postcode over the last 12 published months. That is far more precise than the title alone, though it never names area_summary or area_rankings to make the sibling boundary explicit.

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?

The fixed-radius, postcode-anchored scope implies when this is the right tool versus area-level siblings, but no sentence states 'use this instead of X when...' or any exclusion. An agent must infer the routing rule from the scope wording alone.

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