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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds the partial-behavior hint that omitting mile switches the tool into route-ID resolution, but leaves open what 'posted vs calculated' means, what happens on an unknown route/state, or how results are truncated. With annotations carrying the safety burden, this is adequate but thin.

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 opening sentence is well front-loaded, but the remainder reads as boilerplate meta-instructions ('Follow its required fields and exact choices', 'Do not pass the REST calculator field inside MCP arguments') that consume space without telling the agent anything schema-derived. The one high-value clause, about omitting mile, is buried mid-paragraph.

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, so return-value explanation is rightly omitted, and annotations cover the safety profile. Still, for a nested two-parameter tool with 0% schema description coverage, the definition should define state/route input conventions and drop the stale 'units' reference; as written the agent can call it but may mis-shape arguments.

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, and it does partially: it explains that fields belong in the nested 'inputs' object and that 'mile' is optional while required fields must be followed. However it never explains the 'state' two-letter format or the 'route' pattern, and it references a 'units' field that does not exist in the schema, which is actively confusing for a 0%-coverage nested 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?

The description uses a specific verb and resource: 'Find exact posted or calculated route and mile references from the BusCalc map index,' which tells an agent this returns mile-marker/route references rather than map geometry or trip plans. It does not explicitly differentiate itself from nearby siblings such as buscalc_map_road_report_search or buscalc_map_bridge_screen, but the resource is concrete enough to select on.

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?

'Omit mile to resolve route IDs' gives one useful conditional case, implying a lookup-by-route vs lookup-by-mile distinction. There is no statement of when to prefer a sibling tool (road report search, bridge screen) or any exclusion, so guidance 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.