openbusdata

plan_journey

Plan a bus journey from a start stop to a destination, arriving by a specified time. Supports direct routes or one change, with optional day filter.

Instructions

Plan a journey from stop_a to stop_b arriving by a given time. Supports direct routes and single changes.

Parameters: stop_a: Starting stop (NaPTAN code or name). stop_b: Destination stop (NaPTAN code or name). arrive_by: Target arrival time (HH:MM, 24h format). day: Optional day filter: mon, tue, wed, thu, fri, sat, sun. Defaults to today. max_changes: Maximum number of bus changes (0 = direct only, 1 = one change). Default 1.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "stop_a": "<stop_a>",
      "stop_b": "<stop_b>",
      "arrive_by": "<arrive_by>"
    },
    "name": "plan_journey"
  }
}

Input Schema

Name	Required	Description	Default
`day`	No
`stop_a`	Yes
`stop_b`	Yes
`arrive_by`	Yes
`max_changes`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.2Jul 6, 2026

TDQS

A4.3/5.0

Behavior3/5

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

No annotations, so description must provide transparency. It explains basic behavior (plans journey with changes) but does not disclose what happens if no journey found, or if multiple options exist. Output schema exists but not detailed in description.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Extremely concise: one sentence for purpose, then a clear parameter list. No redundancy, every sentence adds value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Covers key aspects: purpose, parameters, constraints. Lacks details on error handling or output format, but output schema exists. Adequate for a tool with moderate complexity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 0%, and description provides full parameter explanations, including formats (HH:MM), possible values (day filter), and defaults. Adds significant value beyond bare schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Clearly states verb (plan), resource (journey), and scope (from stop_a to stop_b with arrival time). Distinguishes from sibling tools like find_routes_between_stops which lists routes, or find_buses_by_arrival_time which finds buses, not plans a journey.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Implied usage for journey planning with arrival time constraint. Supports direct routes and single changes, but doesn't explicitly say when not to use or provide alternatives. However, it's clear enough for an agent to infer context.

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

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