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

Annotations declare readOnlyHint=false, idempotentHint=false, destructiveHint=false; the description adds real context beyond that — payment to the seller, deal closure, zero cost, and that the action is irreversible. It doesn't cover authorization mechanics beyond the buyer secret or what a repeat call does, so it isn't exhaustive.

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 clauses, zero filler, and the outcome ('seller is paid now and the deal closes') is front-loaded ahead of cost and prerequisites.

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?

With no output schema, the description carries the burden of describing the result and does so (seller paid, deal closed, irreversible), plus cost and required credentials. It leaves only minor gaps such as error/failure behavior on a re-confirm.

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 both parameters are already documented with format details (agp_ + 32 hex). The description only restates that the deal id and buyer secret are required, adding no syntax or format meaning beyond the schema — the baseline 3 applies.

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?

The description gives a specific verb+resource ('Confirm a deal') and immediately states the concrete effect: 'the seller is paid now and the deal closes.' That distinguishes it from get_deal/list_deals/create_deal in practice, though it never names or contrasts a sibling explicitly.

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?

It states the actor/role precondition ('as its buyer'), the cost ('Free'), the required inputs, and the irreversibility ('Confirming is final') — enough context to know when this applies. It stops short of naming when NOT to use it or pointing to alternatives like get_deal for inspection.

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