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

Annotations already declare readOnlyHint, idempotentHint, and closed-world behavior, so the safety profile is covered. The description adds genuinely new operational context: UK-only availability, zero cost, and a full inventory of what the register reports. It does not describe failure modes for invalid area identifiers, which is a minor gap.

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 tool's identity and the 'read before the data' directive, followed by the content inventory. The parenthetical field list is long but each item conveys what the register measures; a small amount of trimming is possible but nothing is truly 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?

An output schema exists, so return-format details are unnecessary. Given a one-parameter read-only tool, the description covers purpose, usage timing, input formats, geographic scope, and cost — everything an agent needs to call it 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 coverage is 0% and the single `area` parameter has no description, so the description carries the full burden. It fully compensates by spelling out three accepted formats: a GSS code (E09000032), a local authority name (Wandsworth), or a warehouse area id, with a concrete example.

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 (read) and resource (data-coverage register for a local authority), then enumerates exactly what it reports: per-field non-null/source shares, designation flags, lease/hereditament counts, planning coverage, and dated listing stock. This is clearly distinguishable from sibling tools like area_stock_profile or area_report, which return the data itself rather than coverage metadata.

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 explicit when-to-use direction: 'read it before the data' and 'State the coverage before quoting a share from a thin field.' It also states scope limits (UK only) and cost (Free). It stops short of naming an alternative tool for when coverage is adequate, but the usage condition is unambiguous.

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