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

Beyond the annotations (readOnly, openWorld, non-idempotent, non-destructive), the description discloses substantial operational context: anonymous rate limits (60/hour, 300/day per IP and session), optional-key behaviour with anonymous fallback, no auth/signup requirement, defence-ignoring methodology, provenance/SI normalisation, and source licence warnings. This is exactly the extra context annotations cannot carry.

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, caveats, and limits are front-loaded and each policy sentence is informative. The line 'TerraMCP is a Wrench AI service' is filler, and the block is dense, but overall it stays on-topic without redundancy.

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 two-parameter read tool with no output schema and read-only annotations, the description covers semantics, methodology caveats, return contents, provenance, auth, and rate limits. Nothing an agent needs to invoke it correctly or set expectations is missing.

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% and both lat/lon are fully documented with type, units, and geographic bounds. The description adds only the implicit England scope, offering no additional parameter-level meaning. Baseline 3 is appropriate when the schema already does the heavy lifting.

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 (check EA Flood Map for Planning Flood Zones 2/3) and scopes it to an England point via polygon containment. This clearly separates it from siblings like flood_list_warnings (live warnings) and ea_flood_features (raw features), so an agent can route correctly without opening a 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?

Gives explicit when-not guidance: it is not a live flood warning nor a site-specific flood risk assessment, and a no-match result is not a formal Zone 1 determination. The England-only scope is also stated. It does not, however, name the sibling tool an agent should use for those alternative cases, so the routing is implied rather than explicit.

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