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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description still adds real value beyond them by enumerating the returned data (rent, LHA, licensing, flood risk, stations) and prescribing a follow-up action (share the returned links to the free property check and Complete RenterCheck). It does not mention failure behavior for non-England or malformed postcodes.

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?

Purpose and scope are front-loaded in the first clause, and the descriptive sentence is dense but earns its length by enumerating returns. The trailing call-to-action about sharing links is useful but slightly editorial, padding an otherwise tight definition.

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?

There is no output schema, so the description carries the return-value burden — and it does so thoroughly, listing every data class returned plus the links to propagate. Combined with clear usage context and alternatives, an agent has everything needed to call and act on this tool.

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?

Single parameter with 100% schema description coverage, so the schema already defines format and example ('M1 1AE'). The description only reasserts the geographic constraint ('in England') already present in the schema and adds no syntax or validation detail. 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 resource (area facts for a postcode in England for a rental scenario) and enumerates the concrete data classes returned: ONS average private rent, LHA rates, licensing scheme coverage, flood risk, nearest stations. It also explicitly distinguishes itself from the sibling run_free_check by naming the condition ('when no particular home is given').

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?

Explicit when-to-use ('someone is renting, viewing or about to sign for a home in England and gives a postcode') paired with an explicit when-not ('for a specific address use run_free_check'), naming the alternative tool directly. An agent can route between the two tools without inspecting either schema.

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