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

With annotations only covering the safety profile (readOnly, openWorld, non-idempotent, non-destructive), the description carries a lot of extra behavioral weight: licence terms checked and attribution retained, incomplete coverage caveat, provenance returned, SI normalisation of hydrological units, and concrete rate limits (60/hour, 300/day per IP and session) with anonymous fallback after quota. This is information an agent cannot get from the schema.

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?

The core spatial purpose is front-loaded, which is good, but the paragraph is padded with material that does not help select or invoke the tool, notably 'TerraMCP is a Wrench AI service' and the closing source-licence remark. The quota and licence sentences do earn their place; the branding does not.

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?

For a five-parameter read-only spatial lookup with no output schema, the description covers what an agent needs: what is searched, the spatial semantics, what is returned (source data and provenance), the normalisation applied, the incompleteness caveat, and the authentication/rate-limit regime.

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 the schema already documents lat, lon, limit, dataset and radius_km with bounds and enums. The description adds only the bounding-box vs radius framing, which the schema's radius_km description already states. 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?

The description names a specific verb and resource ('Find England planning dataset entities intersecting a bounded WGS84 box around a point') and enumerates the datasets covered, so an agent knows exactly what comes back. It does not explicitly distinguish itself from overlapping siblings such as flood_zone_at_point or ea_flood_features, which also serve flood data, so it stops short of a 5.

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?

Usage context is implied rather than stated: the agent learns this is open data needing no key, is rate limited, and is 'not a planning determination', but there is no explicit guidance on when to choose this tool over the sibling flood/designated-site tools. No alternatives or exclusion conditions are named.

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