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

Annotations already declare the tool as read-only, non-destructive, and idempotent. The description adds value by detailing the output fields (current station, delay, schedule, etc.), which helps the agent understand what to expect. No contradictions with annotations.

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 a single, well-structured sentence that front-loads the purpose and lists key outputs. No wasted words, and all information is essential.

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 low-complexity read tool with full schema coverage and an output schema, the description covers the necessary aspects: it identifies the resource (Indian train), the input constraints (today or specific date), and the outputs (current station, schedule, delay). It is sufficiently complete for an agent to use the tool correctly.

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 coverage is 100%, so the baseline is 3. The description does not add significant new meaning beyond the schema; it mentions 'today or a specific date' which relates to start_day but doesn't clarify the offset semantics. Schema already describes parameters adequately.

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 description clearly states the action ('Get live running status'), the resource ('Indian train'), and the specific data returned ('current station, expected arrival/departure, delay, distance covered, full station-by-station schedule'). It effectively distinguishes itself from sibling tools like irctc.trains.search and irctc.stations.search by focusing on live status of a specific train.

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 explicitly mentions usage context: 'for today or a specific date', which guides the agent on when to use this tool. It does not explicitly state when not to use or provide alternatives, but the context and sibling names imply the tool is for real-time tracking of a known train number.

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