trains

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

With no annotations, the description carries the full behavioral burden. It usefully discloses the precondition that writes must target exactly one explicit train_id and that the schedule field follows Factorio's TrainSchedule structure, plus the boundary that groups/interrupts are out of scope. It omits what a call with all-null arguments returns, whether a schedule replacement is destructive, and how the five optional fields interact when combined.

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?

Two dense sentences with the primary read/write purpose front-loaded and the caveat about advanced scheduling after it. No filler, though the semicolon-joined second sentence reads as a stack of caveats rather than a clearly ordered structure.

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?

An output schema exists, so return values need not be described. But for a five-parameter, unannotated tool that both reads and mutates train state, the description leaves too much open: parameter meanings, the all-null default behavior, and the effect of mutations are all absent.

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 0% across five parameters, so the description must compensate and largely does not. It explains only 'schedule' (TrainSchedule structure) and the intent of 'train_id'; 'surface', 'manual_mode', and especially 'go_to_station' (typed as an integer, which is non-obvious for a station target) are left entirely undefined.

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 first clause names a concrete verb+resource pair ('Inspect trains, schedules and carriages') and the second states the write path ('modify one explicit train ID'). The read/write duality is stated plainly, though the combined scope makes it slightly harder to tell which mode a bare call triggers. It does gesture at a sibling ('get_schedule() in the advanced Lua tool'), which helps separate it from execute_lua.

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?

'modify one explicit train ID when requested' implies a prerequisite (train_id must be supplied for any mutation), and the note about groups/interrupts routes advanced scheduling work to execute_lua. However, no guidance is given for the other likely alternatives in the sibling list (inspect_entity, configure_entity, move_to), and nothing says when to call this with no arguments versus a populated one.

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