plan_journey

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

No annotations are provided, so the description carries the full burden. It does not say what modes are considered, whether results are real-time or scheduled, whether alternative routes are returned, or whether the call is read-only and rate-limited.

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?

A single short sentence, front-loaded with verb and resource, with no filler. Everything present 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 no annotations and no output schema, the description should explain the nature of the result (route options, modes, steps). It leaves an agent unable to predict the response shape for a fairly complex planning operation.

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 100% and each parameter already documents format and examples (postcodes, HHMM), so the baseline of 3 applies. The description adds no meaning beyond the schema, not even clarifying that 'time' is a departure time.

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 (plan) and resource (journey) plus the provider (TfL), which distinguishes it from siblings like get_journey_time and get_line_status. It does not explicitly contrast with those siblings, so it falls short of a 5.

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 phrase 'plan a journey between two locations' implies the usage context, but there is no explicit when-to-use versus get_journey_time or get_disruptions, and no prerequisites (e.g., valid station names, TfL coverage).

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