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

Goes well beyond the annotations: it discloses third-party data sharing (name, phone, address, problem description sent to Renzy), the downstream human follow-up (Renzy phones to confirm), the absence of payment collection, and the non-idempotent side effect with a 'do not retry a call that succeeded' warning. This is exactly the context annotations cannot convey.

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?

Five tight sentences, front-loaded with the action and immediately followed by the prerequisite, the human confirmation step, the data-sharing disclosure and the retry warning. No sentence is redundant.

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 a 6-required-parameter write tool with no output schema, the description covers the call contract, side effects and misuse risk thoroughly. The only gap is that it never says what a successful call returns (e.g. a booking reference), which matters since there is no output schema to fall back on.

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 description coverage is 100%, so each of the 8 parameters is already documented. The description adds only the provenance of slot_id (from check_availability) and the confirmation of the address/rate, which the schema largely covers; the baseline 3 is appropriate.

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 and resource ('Book a Renzy plumber') plus the scope constraint ('one arrival window') and the destination ('the customer's address'). It is clearly distinguishable from siblings check_availability, quote_installation and order_installation.

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 and the correct sequencing ('Call check_availability first and use a slot_id it returned') and an explicit pre-call obligation ('Confirm the window, the hourly rate and the address with the customer before calling this'). It also names the retry exclusion, which is the main misuse risk.

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