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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds the endpoint path `/trains/pnrstatus` but does not disclose additional behavioral details such as response characteristics or error handling; this is acceptable given the annotations but not especially rich.

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 two sentences long, front-loaded with the core purpose, and includes the endpoint without unnecessary filler. Every sentence earns its place.

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 simple, read-only, single-parameter tool with an output schema and clear annotations, the description is largely complete. It could have added a brief note about when to prefer this over railway_train_liveStatus, but the core information needed to select and invoke the tool is present.

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%, with the single `pnr` parameter fully described as a 10-digit PNR number, including min/max length and an example. The description merely restates this information, adding no new semantic value beyond the schema.

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 tool checks ticket PNR status using a 10-digit PNR number, using a specific verb and resource. It distinguishes itself from sibling tools like railway_train_liveStatus by explicitly referring to 'ticket PNR status' rather than train status.

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 opens with 'Use this tool to check ticket PNR status,' which gives an explicit purpose but does not discuss when not to use it or compare it with alternatives. Usage context is implied rather than fully articulated.

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