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

Annotations already cover safety (readOnly, idempotent, openWorld, non-destructive), so the bar is lower, and the description still adds real behavior context: distances are straight-line rather than road distance, coverage is uneven by source and category, and facility status/road access are not validated here. That materially changes how an agent should interpret and present results.

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 first three sentences are well front-loaded and earn their place. The trailing sentences ('Put tool fields inside inputs', 'Supply units... only when listed in inputSchema', 'Do not pass the REST calculator field inside MCP arguments') are generic boilerplate that restates the schema envelope, adds noise, and even mentions a nonexistent 'units' field.

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 and annotations are rich, so return values and safety need not be described. Still missing for a nested-object, low-schema-coverage lookup: what the kind categories mean, how results are ordered or capped by limit, and why an agent would pick this over sibling landmark/community/marker tools.

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 0%, so the description must compensate. It does explain the radius semantics ('straight-line miles', 1 to 50), which the schema does not, but it never explains the kind enum categories or limit behavior, and its 'Supply units or modelVersion' sentence references a units field that does not exist in the schema.

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 ('Find published map reference landmarks') plus a hard scope constraint ('within 1 to 50 straight-line miles'). The resource noun differs from the sibling buscalc_map_nearby_communities, but the description never explicitly contrasts the two, so differentiation is left to the name.

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?

'Coverage varies by source and category' and 'Verify road access and facility status separately' imply this is a coarse reference lookup whose results need follow-up verification, which is useful implied usage guidance. However, it never says when to prefer this over nearby_communities or marker_lookup, and gives no exclusions.

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