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

Goes well past the destructiveHint annotation by disclosing real side effects: Splose may send the patient booking confirmations or reminders per practice settings, the appointment becomes invoiceable later, and duplicate calls book duplicates. These are exactly the consequences an agent needs before invoking a write.

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?

Four short sentences, front-loaded with the WRITE marker and the core operation, then the side effects, then the prerequisite, then the idempotency warning and endpoint. Every sentence carries distinct information; nothing is repeated from the schema.

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?

For an 8-parameter write with no output schema, the description covers purpose, side effects, prerequisites and idempotency, which is nearly everything needed. The one gap is the return value — it never says whether the created appointment (and its id) comes back, which matters for chaining into splose_update_appointment or invoicing.

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?

Schema coverage is 100%, so the schema already defines every field and its UTC semantics; the baseline is 3. The description adds real value by tying the id parameters to their concepts in a single sentence and making the singular cardinality explicit ('one patient with one practitioner, service and location').

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?

States a specific verb ('books') and resource ('appointment') with explicit cardinality and entity bindings: one appointment, one patient, one practitioner, service and location, spanning start to end in UTC. The 'WRITE:' prefix and singular scope let an agent distinguish it immediately from splose_update_appointment and splose_list_appointments.

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?

Gives an explicit prerequisite ('Check splose_find_free_slots first') naming the sibling tool and the condition that selects it, plus a non-idempotency warning that shapes retry behaviour. It stops short of a negative case (e.g., use splose_update_appointment to modify an existing booking rather than re-creating), so not a full when/when-not pair.

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