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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds scope and cost context not present anywhere else: 'UK only. Free.' It also previews the return shape. No failure modes or rate limits are mentioned, so not a 5.

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 short sentences, zero filler, with the core capability and the routing rule front-loaded before the scope/cost note. Every sentence carries information.

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?

The description covers purpose, routing, geography scope, cost, and an output preview, and an output schema exists so return values need not be restated. The remaining omission is guidance on the optional H3 parameters, which are undocumented in both schema and prose.

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 0% and the description never addresses include_h3 or h3_resolution — an agent cannot tell what H3 output is or when to enable it. Only the required area_name is given indirect meaning via the examples 'Hackney' and 'E5'.

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 concrete verb (resolve) plus the resource and the exact outputs (area_id, centroid, hierarchy breadcrumbs), with an input example ('Hackney', 'E5'). This clearly separates it from address_resolve and area_reverse_geocode, which key off addresses or coordinates rather than names.

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?

'Call this first when a question is about a named area rather than a specific address' gives an explicit entry-point rule and implicitly contrasts with the address-based siblings. It does not name an alternative tool outright or state when-not to use it, so it falls short of a 5.

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