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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds genuine behavioral detail beyond that: it returns up to 5 candidates ranked best-first, and includes county/region where known. It stops short of covering latency or failure behavior for unresolvable queries, 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 sentences, each doing distinct work: what it returns, when to use it, and where the result goes next. Front-loaded with the capability rather than burying it behind preamble.

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 no output schema, the description carries the burden of describing return values and does so: up to 5 candidates, best-first ordering, county/region included. Combined with the downstream handoff instruction, an agent has everything needed to call and use this tool 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?

There is a single parameter with 100% schema description coverage including examples ('Newport', 'Shoreditch', 'BS1'). The description reinforces the accepted input domain (place name or postcode) but adds no syntax or format rules beyond what the schema already states, so the baseline 3 applies.

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 (resolve) and resource (UK place name or postcode) plus the outputs produced (coordinates and matching search page). This is clearly distinguishable from siblings like search_trainers and get_trainer_profile, which operate on trainers rather than locations.

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 an explicit trigger ('when a place name is ambiguous (there are many Newports)') and an explicit next step ('pass the chosen latitude/longitude to search_trainers'). The handoff to a named sibling tool leaves nothing to inference.

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