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

Annotations already declare readOnly, idempotent and openWorld, so safety is covered. The description adds behavior the annotations cannot: results are ordered oldest first per crime, ids not held by data.police.uk are listed rather than silently omitted, and the 25-id cap is stated. This is meaningful operational context beyond the structured hints.

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 dense sentences with no filler; the core action and the id cap lead, followed by return ordering and the ABS caveat. Well front-loaded, though the clause about ids data.police.uk does not hold is slightly compressed and could read ambiguously.

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?

Given a fully documented single parameter, an output schema, and annotations covering safety, the definition supplies everything needed to invoke correctly: input source, limit, ordering, and the ABS edge case. Return-value details are legitimately delegated to the output 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 coverage is 100% and the schema already documents the 64-hex pattern, 1–25 range and comma/space tolerance. The description still adds provenance (the id comes from the persistent_id field of two named sibling tools) and reinforces the 25-item ceiling, which is the parameter's most consequential constraint.

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 ('Fetch the full police outcome history of up to 25 crimes by persistent_id') and names the sibling tools that supply the input id, so an agent can distinguish it from ukcrime_search_crimes and ukcrime_search_outcomes without opening a 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?

It tells the agent where the required id comes from (the persistent_id field of ukcrime_search_crimes / ukcrime_search_outcomes) and adds a real exclusion ('Anti-social behaviour records carry no persistent id'). It stops short of an explicit 'use this instead of X when Y' statement, so it is clear context rather than full routing guidance.

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