compare_placesTwo UK areas of the same level side by side on the same published figures, each with its own period and source. Key figures by default.
| Name | Required | Description | Default |
|---|---|---|---|
| a | Yes | An official area code (E09000012), a page slug (hackney) or path, or an exact place name. | |
| b | Yes | An official area code (E09000012), a page slug (hackney) or path, or an exact place name. | |
| layers | No | Optional layer ids to compare. |
Changes observed during successful MCP inspections.
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 usefully adds the same-level constraint and that each side may carry a different period and source, plus the default that only key figures are returned, but says nothing about response shape or limits.
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 compact sentences with the constraining conditions (same level, same figures) front-loaded and zero filler. Every clause contributes information an agent can act on.
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 must carry more of the return-value burden, and it only gestures at it via 'key figures by default'. For a comparison tool this is adequate but leaves the agent guessing about output structure and whether extra layers can be requested per side.
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%, so a 3 is the baseline. The description adds real meaning beyond the schema by disclosing the default behavior of the optional layers parameter ('key figures by default') and clarifying that the period/source can differ per side, which the schema does not convey.
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?
The description states a specific operation and resource: two UK areas placed side by side on the same published figures, restricted to the same area level. It implicitly contrasts with single-place siblings (get_place, fetch), though it never names them or explicitly says it is not for one-place lookups.
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?
A usage condition is embedded in the first clause ('same level', 'same published figures', 'each with its own period and source'), so an agent can infer the tool is for area-vs-area comparison. However, it never states when to prefer this over get_place or search_places, and no exclusions are given.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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