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

Annotations declare destructiveHint=true and idempotentHint=false, and the description adds meaningfully beyond them: the actor restriction (buyer only, not the accepted bidder), the irreversible payout of 90% of held funds to the seller's Stripe account, and the hard failure when Stripe Connect onboarding is incomplete. This is exactly the side-effect detail an agent needs before a destructive, non-idempotent call.

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 tight sentences: purpose/transition first, then the authorization constraint, then the financial side effect and failure mode. No filler, and the most important routing fact (who may call it) is front-loaded.

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 one-parameter destructive mutation with no output schema, the description covers preconditions, state change, money movement, and failure mode. It could note what is returned or what happens to the remaining 10% of held funds, but nothing critical to invoking it correctly is missing.

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?

There is a single parameter, job_id, whose schema description ('The job's UUID') already covers it at 100% coverage. The description adds no format, sourcing, or lookup guidance beyond the schema, so 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?

States a specific verb+resource (mark a job complete) and names the exact state transition (in_progress → completed), which cleanly separates it from sibling mutations like cancel_job or request_close. An agent can identify the operation without opening the schema.

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 clear preconditions: the caller must be the job's buyer, and the job must be in_progress. It does not name alternative tools (cancel_job, request_close) or state when completion should not be used, so it stops just short of explicit when-not guidance.

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