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

Annotations only provide readOnlyHint=false and destructiveHint=false, so the description carries much of the burden. It usefully notes that both origin and destination are required for correct map routing, but it does not disclose other behavioral details such as side effects beyond item creation, validation outcomes, or what the response contains. This is adequate but not 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?

Two concise sentences deliver the core purpose, the sibling exclusion, and the critical usage constraint. Every sentence earns its place and the most important routing instruction is front-loaded.

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 17-parameter tool with no output schema, the description covers purpose, required parameters, and the key alternative. The schema fully documents optional parameters, so the description does not need to repeat them. A small gap remains around what happens after a successful add (e.g., return value or generated item location), but overall this is complete enough for safe 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 coverage is 100%, so the baseline applies: the schema documents all parameters thoroughly. The description adds the key guidance that origin and destination are both required and highlights transport type examples, but it does not meaningfully extend parameter meaning beyond the schema. This meets the baseline without exceeding it.

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 uses a specific verb ('Add') and resource ('transport item ... to a trip'), lists the supported transport types, and explicitly distinguishes itself from trip_item_add. An agent can clearly understand what this tool does and why it exists.

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 states 'ALWAYS use this instead of trip_item_add for transport,' naming the sibling alternative and the exact condition for choosing this tool. It also clarifies the required origin/destination fields and their purpose, leaving no ambiguity about when to invoke it.

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