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

Annotations indicate a non-read-only, non-idempotent write operation. The description says 'Add', which aligns with creating a new entity. However, it does not mention potential side effects (e.g., required fields beyond journey_id and title, validation rules, or linkage to journeys/stops). The annotations cover the basic safety profile, but the description adds little beyond the action itself.

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 a single, concise sentence with no redundant information. It efficiently conveys the core function without unnecessary elaboration, making it easy for an agent to parse.

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?

Given the tool's complexity (18 parameters, dual purpose), the description is under-specified. It does not explain the difference between an activity and a travel leg, nor does it mention required vs. optional fields beyond what's in the schema. There is no indication of return values, errors, or integration with journeys, limiting the agent's ability to use the tool effectively.

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 has many fields (18), and only a few have descriptions (stay_id, travelers, start_datetime, end_datetime, transport_mode). The description does not clarify the purpose of most parameters (e.g., emoji, price, category, currency, booking_url, place_name, country_code). It provides a high-level hint about 'thing to do' or 'travel leg' but fails to explain which parameters are relevant for each case, leaving significant ambiguity.

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's function: adding a 'thing to do' or a 'travel leg' to a trip, optionally attached to a stop. This distinguishes it from sibling creation tools (e.g., create_accommodation) which serve different entity types. The mention of 'travel leg between places' adds specificity about one of its dual use cases.

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 activities and travel legs but does not explicitly state when to choose this tool over alternatives. It lacks guidance on scenarios such as when to attach to a stop or how to differentiate between activity and travel leg inputs. The sibling tool names provide context, but the description itself does not offer clear selection criteria.

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