Plan a bike route

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

With no annotations, the description carries the full burden and does well: it discloses the return payload (distance, climb, time, surfaces, turn instructions, shareable link), optional file saving, coordinate/place-name waypoints, and the large-GeoJSON caveat. It does not mention failure modes, rate limits, or network dependency, but the core behavioral surface is well covered.

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?

Three sentences cover the core action, output payload, waypoint flexibility, and optional saving behavior with no filler. Important details are front-loaded in the first sentence, and the later sentences add only necessary nuance.

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?

Given a complex schema with 12 parameters and no output schema, the description effectively summarizes what the tool returns and the key modes of use. It names most salient behaviors but leaves some output structure details (e.g., exact JSON shape, units) implicit; still, the description is sufficient for an agent to understand what the tool does and when it is appropriate.

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 the schema already documents all 12 parameters and their meanings. The description adds a helpful high-level characterization of waypoints (coordinates or place names) and optional GPX/GeoJSON/KML export, but this overlaps with existing parameter descriptions rather than substantially extending them.

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 names a specific verb ('Plans a cycling route'), a specific engine (BRouter), and a detailed list of outputs, which makes the tool's purpose unmistakable. It clearly differentiates from its siblings (profile comparison, geocoding, profile listing/options) without needing to mention them.

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 the tool is for routing through waypoints and references list_profiles/get_profile_options for related configuration, but it never explicitly states when to use plan_route versus an alternative or when not to use it. The context is clear enough from the purpose, but no direct usage-selection guidance is provided.

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