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

Annotations already cover read-only and non-destructive. The description adds behavioral nuance beyond that: it states that the tool returns date-specific content, that its images are only supplementary booking context, and that boat_details is the canonical media source. This prevents misuse and clarifies the data source, even though it doesn't describe fine-grained response details.

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 compact paragraph with each sentence earning its place: it states the result, gives the source requirement, excludes media-only calls, clarifies image usage, and provides the booking flow. It is not terse to the point of losing meaning, but it avoids irrelevant details. The structure is logical and front-loaded with the tool's purpose.

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 there is no output schema, the description tells the agent what to expect from the tool: availability, pricing, extras, and booking choices. It also covers the all-important interaction contract with search_boats and booking_detail_mod. It could better describe the output shape or error behavior, but for the agent's invocation it is sufficiently 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 description says 'Use id_boat and id_tbf1 exactly as returned by search_boats', but the schema already states that for both parameters. With 100% schema coverage, the description adds no new parameter meaning beyond what the schema provides. It hints at 'date-specific' and 'selected yacht' but those map to existing params without adding format or semantics. Thus, the baseline 3 fits.

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 opens with a specific verb and resource: 'Return date-specific availability, pricing, extras and booking choices.' It also explicitly distinguishes itself from boat_details for media ('Do not call this tool only to see yacht photos or media'). This grounds the purpose and disambiguates it from siblings without needing to inspect the schema.

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 gives explicit when-to-use and when-not-to-use guidance: it is 'for a selected yacht and charter period', and immediately tells the agent to call boat_details for media. It also directs the next step in the workflow: after modifications, use booking_detail_mod and its server-calculated totals. No room for ambiguity.

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