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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety profile is covered. The description adds useful context beyond them: what the full record contains (name, dataset, publisher reference, dates, documentation URL) and the cost implication of the geometry flag ('the WKT boundary when asked for'), matching the schema's tens-of-KB warning.

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: purpose and id source front-loaded, then the return payload, then a copyable example. No filler and nothing buried.

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 that burden itself — and it enumerates the returned fields and the optional geometry. Combined with 100% schema coverage and full annotations, an agent has everything needed to call this 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 100% and both params are self-documented, so the baseline is 3. The description goes slightly further by showing the include_geometry flag as an opt-in that governs whether the geometry is returned at all, plus a concrete invocation example, which helps the agent choose the flag value.

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 (Fetch) and resource (one UK planning entity) keyed by numeric entity id, and names the sibling tools (ukplanning_search, ukplanning_entities_at_point) that produce that id. An agent can distinguish this single-record lookup from the search/list siblings without opening any schema.

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 parenthetical '(from ukplanning_search or ukplanning_entities_at_point)' makes the intended workflow explicit — this is the fetch step after a search. It does not state when not to use it (e.g. for bulk retrieval), so a 4 rather than 5.

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