get_train_by_number

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

No annotations, so the description carries the full burden; it signals the response is 'quick ... basic details', implicitly distinguishing it from live/real-time tools like get_live_running_status. However, it never states that it is a read-only lookup, how it behaves for an invalid train number, or whether running-day data can vary — meaningful gaps for a zero-annotation tool.

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?

One well-formed sentence with the resource and returned fields front-loaded and no filler. It could be slightly tighter ('quick train basic details' is redundant with 'official train name...'), but it is efficient.

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?

For a one-parameter lookup with no output schema, enumerating the returned fields compensates well and tells the agent what it will get back. Missing only edge-case behavior (invalid numbers, static vs. live data scope) to be fully complete.

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 the single train_no parameter already documents its 4-5 digit format with an example. The description adds no further parameter meaning, so the baseline 3 applies.

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?

Clear verb+resource: retrieves basic train details by number, and enumerates the fields returned (name, type, origin, destination, running days, distance). It does not explicitly contrast with search_trains or search_trains_by_name, so sibling differentiation is only implicit via 'by train number'.

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?

Usage is only implied by the phrase 'by train number' — the agent must infer it should be used when a numeric train ID is known rather than a name or route. No alternatives (search_trains_by_name, search_trains, get_live_running_status) are named or excluded.

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