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

Goes well beyond the annotations (readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false) by disclosing the 5-minute hold semantics, that the hold is not a booking, the confirm_url return contract, the two possible downstream outcomes (instant booking vs office accept/decline), and the fallback to phone contact options when online booking is unavailable.

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?

Front-loaded with the hold and the not-a-booking warning, then the required next action, then the outcome branches. Every sentence carries a distinct instruction; nothing is filler.

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?

An output schema exists, so return-value documentation isn't required, yet the description still surfaces the critical confirm_url field and its required handling. Combined with the mutation-outcome branches and the fallback case, an agent has everything needed to call this correctly.

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 the baseline is 3. The description only reinforces the start parameter ('use a start_local value from get_availability') and says nothing extra about mode, lang, reason, or client_name beyond what the schema already documents.

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 the specific action and its scope precisely: it holds one free slot for 5 minutes and explicitly does NOT book. The negation ('This does NOT book the appointment') makes the boundary against its siblings and against the user's expectation unmistakable.

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?

Explicitly routes the agent: use a start_local value from get_availability, then immediately show the confirm_url and instruct the user to open it, enter phone + SMS code, and confirm. It also states what must never be said ('never say the appointment is booked').

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