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

The description explicitly notes it is a WRITE operation and mutates data, and explains the behavior of destination re-resolution and points replacement. However, it lacks details on authentication requirements, error handling, idempotency, or what happens if the trip does not exist. With no annotations, the description carries the full burden but provides only moderate behavioral context.

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 concise, with 4 sentences plus an endpoint header and warning. Each sentence adds essential information. It uses formatting effectively to highlight important points like the points behavior and the write warning. No wasted words.

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?

The description adequately covers input parameters and usage, but lacks information about the output or return value. Since there is no output schema, the description should explain what the tool returns (e.g., the updated trip object). It also does not mention error cases. This gap reduces completeness for a mutation tool.

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?

The input schema has 100% coverage, so baseline is 3. The description adds significant value beyond the schema: it clarifies that only include fields to change, explains how destination change triggers re-resolution, and details points replacement behavior. This additional context justifies a score above baseline.

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 identifies the tool as an update operation for a trip, with the verb 'Update' and resource 'trip'. It distinguishes itself from sibling tools like trips_create and trip_delete by focusing on modifying existing trips. The endpoint pattern reinforces this purpose.

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 provides clear usage instructions: only include fields to change, how to handle destination updates with placeID or eventID, and that points replacement is not a patch. It warns about the write nature but does not explicitly state when to use this over alternatives like trip_delete or trips_create, though context implies differentiation.

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