Get nearby bus stops

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

Annotations already indicate readOnlyHint=true and idempotentHint=true. The description adds rich behavioral context by detailing the return structure, field notes (e.g., 'buses[].arrivalTime is a ms timestamp', 'capacity: 0=light, 1=moderate, 2=crowded'), and real-time behavior. No contradictions.

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 description is lengthy but well-structured: purpose first, then usage guidance, then parameter explanation, then full return example with field notes. Every section adds value; no filler. Could be slightly more concise, but overall well-organized.

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?

Despite no output schema, the description provides a complete return schema with detailed field notes covering all return fields. It explains how to obtain coordinates, parameter specifics, and response format. For a tool with 5 params and complex output, this is thorough and fully contextual.

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 coverage is 100%, so baseline is 3. The description adds extra semantics beyond the schema, e.g., 'limit: how many of the closest stops to return (max 20)' and response_format explanation. It also clarifies the city_id format. This lifts the score to 4.

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 explicitly states 'List bus stops near a WGS-84 GPS coordinate, each annotated with the lines that pass through and the realtime buses approaching.' This clearly defines the verb (list), resource (bus stops), and scope (near coordinates with lines/realtime), distinguishing it from siblings like bus_get_stop_detail (specific stop) and bus_search (by 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?

The description provides explicit guidance: 'If you don't have coordinates: call bus_get_my_location first... or ask the user for a landmark and resolve it via bus_search.pois.' This tells the agent when to use alternatives, clearly separating this tool from coordinate-requiring tools.

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