plan_traction

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

The description usefully reveals that the assignment is greedy, minimizes changes, and treats uncovered runs as non-errors. However, it mentions 'unmatched signalling' as a cause of uncovered runs without noting that this depends on require_signalling_match, which defaults to false in the schema. With no annotations present, this ambiguity matters and weakens transparency.

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 three tightly written sentences, starting with the core purpose, then moving to prerequisites, then edge-case behavior. Every sentence adds necessary information and there is no redundant repetition of schema details.

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?

The description covers the essential invocation prerequisites and the unusual 'uncovered, not an error' behavior, and an output schema exists for return-shape information. The main gap is not explicitly clarifying the signalling condition and its default, but the nested schema partially compensates for that.

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 low at the top level, and the description compensates by explaining the relationship between route, section_ids, fleet_ids, and custom_locomotives. It tells the agent where route comes from, that section_ids follows check_train_compatibility semantics, and where locomotive ids originate. The require_signalling_match parameter is left to the schema, but that field already has a detailed description.

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 opening sentence clearly states the verb, resource, and goal: 'Assign locomotives from a fleet to a route's runs, greedily minimising changes.' This distinguishes it from sibling tools like find_route and check_train_compatibility, whose purposes are route discovery and compatibility checking rather than assignment.

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 gives explicit operational guidance: call find_route first and pass its route, or pass section_ids like check_train_compatibility, and provide at least one locomotive via fleet_ids or custom_locomotives. It lacks an explicit 'when not to use this tool' or a direct comparison to a sibling alternative, but the invocation workflow is clear.

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