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

Annotations already cover the safety profile (readOnly, idempotent, non-open-world), so the description wisely spends its words elsewhere: it discloses the normalization denominator, that anti-social behaviour is folded into the counts, that each row carries page_url, and it warns 'these are published rates, not safety ratings.' That interpretive caveat is genuinely useful context beyond structured fields.

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 tight sentences, front-loaded with the scope and metric, ending with a compact caveat. Every clause carries information — geography, denominator, inclusion of ASB, row payload, and the interpretation warning.

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, return-value explanation isn't required, yet the description still sketches row contents (rate, counts, page_url). The main remaining gap is routing: methodology and area_summary exist for definitions and non-ranked views, and the description doesn't mention them.

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 limit/order/category meanings are already documented. The description only adds marginal signal — that an empty category means all street-crime records including ASB, echoing the schema's default. Baseline 3 applies since the schema does the heavy lifting.

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 precise verb+resource ('Postcode districts in England and Wales ranked by published street-crime records') with scope (England and Wales), metric basis (per 1,000 Census 2021 residents) and what each row contains. It is clearly distinguishable from area_summary/postcode_summary by being a ranked list, though it never names those siblings explicitly.

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 by the word 'ranked' — an agent can infer this is the tool for ordered comparisons rather than summaries. But there is no explicit when-to-use/when-not-to-use guidance and no pointer to area_summary or postcode_summary for non-ranked views, leaving the choice to inference.

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