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

Goes well beyond the annotations by disclosing external side effects (patient may be notified via SMS/e-mail/WhatsApp per clinic automation), the past-date constraint, and refusal behavior on taken slots or unknown patients. What is missing is what the call returns (no appointment id mentioned) despite no output schema existing.

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?

Three short sentences, front-loaded with the WRITE marker and the prerequisite, with no filler. Every clause (past dates, prerequisites, notifications, units) carries operational weight.

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?

Covers preconditions, constraints, side effects and the endpoint for a 17-parameter write tool. The remaining gap is the response: with no output schema and no mention of what comes back (e.g. the created appointment id), an agent cannot chain follow-up calls without guessing.

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?

With 76% schema coverage the schema already documents most fields, and the description's one added rule ("valor is in CENTS and must be 0 with insurance") largely restates the value_cents property description. It adds no guidance on the eight required ids or on the insurance/insurance_plan_id pairing beyond what the schema says.

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?

Opens with an explicit verb+resource marker ("WRITE: books a new appointment in the clinic's agenda") and the parenthetical "not in the past" scopes it further. The verb distinguishes it cleanly from feegow_reschedule_appointment, feegow_cancel_appointment and feegow_list_appointments without needing 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?

States a concrete prerequisite ("Check feegow_get_available_schedule first"), names the failure conditions ("a taken slot or unknown patient is refused"), and implicitly routes existing-booking changes to the reschedule/cancel siblings. An agent knows both when and how to invoke this.

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