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

Adds context beyond the annotations: payment is collected at the visit rather than by the tool, and David texts the customer to confirm, which signals an out-of-band follow-up side effect. It does not cover failure handling (e.g. slot taken between find_open_times and booking) or what the call returns, so it is strong but not complete.

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 what happens and the precondition before the mechanical instructions. No repetition of schema content and nothing wasted.

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 mutation with no output schema, the description covers the precondition, the date/block source, the payment model, and the package special case. It is silent on what happens if the booking fails or how confirmation reaches the agent beyond the customer text, which is a modest gap.

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 88%, so the baseline is 3, and the description earns a bump by adding a real cross-field rule the schema never states: for service "package" the block represents the whole day and you should send "Morning". The remaining parameters (name, phone, address, size, gate_or_parking) are left entirely to the schema.

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 a specific verb and resource plus scope: "Books one visit, paid at the visit." It also functionally separates itself from the siblings by making find_open_times the source of date/block, so an agent knows this is the write step and find_open_times is the lookup step.

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 gating condition: only when the person asked you to book and confirmed every field. It also names the prerequisite lookup (pick a date and block from find_open_times) and the special case that applies when service is "package".

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