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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely non-structural context: the tool returns links only, Close Knit never fetches or stores listings, and OpenRent is included for rentals — all useful for an agent deciding whether the output is usable directly.

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 short sentences, zero filler. The resource and portal scope are front-loaded and the 'links only / never fetches or stores' caveat follows immediately after — nothing redundant with the name or title.

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-value structure need not be described, and the description usefully says the result is links to open externally. It is nearly complete; only the relationship between outcodes_per_area and the emitted link count/wording is left implicit.

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 all five parameters are already documented in the schema, which sets the baseline at 3. The description adds only marginal detail (postcode districts, all-portal coverage, rental inclusion for OpenRent) without explaining area_ids, max_price units, or outcodes_per_area ordering beyond what the schema already says.

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 and resource — pre-filtered search links on Rightmove, Zoopla, OnTheMarket (plus OpenRent for rentals) for postcode districts of shortlisted areas. That is concrete and distinct from siblings like evaluate_custom_criterion or get_area_evidence_pack, but no sibling is named as an alternative, so the differentiation is implicit rather than explicit.

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?

The context ('for the postcode districts of shortlisted areas') plus 'open them on the user's behalf to read listings' implies when to reach for this tool: after areas have been shortlisted you want external portal results. But it never states when NOT to use it or names sibling tools that would serve the same need, leaving usage to inference.

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