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

Annotations declare readOnlyHint=false and destructiveHint=false, indicating a non-read, non-destructive mutation. The description adds that the operation adds an item to a trip on a day, but does not disclose side effects, permissions, or limitations. With annotations covering the basics, the description adds marginal 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?

Single sentence, no filler, front-loaded with purpose and examples. Every word contributes value.

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 tool has 6 parameters (4 required) and no output schema. The description covers the core action but omits return value (e.g., response containing the created item) and error conditions. For a simple addition tool, it is adequate but not fully complete.

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 schema covers all 6 parameters with descriptions (100% coverage). The description repeats 'on a given day' and implicitly includes item types via examples, but adds no new meaning beyond the schema. Baseline 3 is appropriate as the schema already does the heavy lifting.

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 verb 'Add', the resource 'item to a saved trip', and lists examples (hotel, flight, activity). It distinguishes itself from siblings like save_trip and list_trips by narrowing to adding items.

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 implies usage for adding various item types to a trip on a specific day, but does not provide explicit when-to-use or when-not-to-use guidance, nor mention alternatives. Given the uniqueness of the tool among siblings, the lack of explicit differentiation is acceptable but not perfect.

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