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

Annotations already convey read-only, idempotent, and non-destructive behavior. The description adds meaningful operational context: session binding and the connector-only restriction. It does not explain possible status values or response shape, but the annotations lower the burden and no contradiction exists.

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 front-loaded with the core purpose and is generally tight. However, the final sentence, 'Only bookings made through this connector can be looked up,' largely restates the first sentence's 'created in this MCP connection' clause, adding minor redundancy.

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 lookup tool, the description covers the essential constraints: session requirement, scope limitation, and fallback for external bookings. The lack of an output schema means return-value details are not specified, but the tool's purpose and annotations make it sufficiently complete for correct invocation.

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%, so booking_id and journey_id are already well documented in the schema. The description adds no parameter-level detail beyond what the input schema provides, so the baseline score of 3 is appropriate.

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 states a specific action, 'Look up the status of a booking,' and a clear resource scope: bookings created in this MCP connection. It distinguishes itself from siblings like cancel_booking and start_booking by focusing on read-only status retrieval and restricting to connector-created bookings.

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?

It explicitly states the prerequisite: the same active MCP session that created the booking. It also gives an alternative path for bookings outside this session, directing the agent to use the secure link in the confirmation email, and clarifies that only connector-made bookings can be looked up.

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