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

The description discloses the exact return fields (short name, description, agency, route type, schedule URL), which is behavioral context beyond the readOnlyHint annotation. It does not mention errors, rate limits, or side effects, but for a read-only fetch these are less critical. The description adds useful information about what the tool returns without contradicting annotations.

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 sentences with no redundant wording. The core purpose is front-loaded, followed by the key detail (ID format) and the discovery hint. Every word earns its place.

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 only one parameter, a readOnlyHint annotation, and an existing output schema (which covers the return shape), the description fully covers what an agent needs: what the tool does, what it returns, the ID format, and how to get IDs if unknown. No essential information is missing for correct invocation.

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?

The input schema already provides a detailed description for routeId, including the agency-prefixed format, an example, and pointers to discovery tools (100% schema coverage). The description repeats the format example but does not add new meaning beyond the schema. Per the rubric, a score of 3 is appropriate when schema coverage is high and the description offers no additional parameter semantics.

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 clearly states the tool fetches details for a specific route by ID, and enumerates the returned fields (short name, description, agency, route type, schedule URL). This distinguishes it from sibling tools like onebusaway_list_routes_for_agency (which lists multiple) and onebusaway_search_routes (which is discovery-focused). The ID format and example remove ambiguity.

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?

The description implies usage context: it's for retrieving a specific route by ID, and it explicitly directs users to onebusaway_find_routes or onebusaway_search_routes for discovering IDs. It does not explicitly state when NOT to use it, but the 'specific route by ID' framing and the discovery guidance effectively communicate the selection criteria. A clear 'when to use' is present, though the 'when not' is implicit.

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