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

Annotations only give the generic safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false). The description adds the substance an agent actually needs: no money is charged at this step, the returned total is fingerprinted and bound to documents/recipient, any change produces QUOTE_STALE, and the tool commits the job to the autonomous payment rail. That side-effect disclosure is exactly the value-add the annotations cannot supply.

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 core promise ('no charge') before escalating to staleness rules and error handling, and each sentence carries distinct information. It is dense and somewhat long, with mild redundancy between the opening 'before any payment authorization is obtained' and the later 'commits the job to the autonomous payment rail,' costing it the top score.

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?

No output schema exists, and the description compensates by enumerating the return payload (subtotal_cents, tax_cents, total_cents, currency, pricing fingerprint, accepted authorization types). It also covers the two meaningful failure modes (QUOTE_STALE and ADDRESS_UNVERIFIED) with remedies, which is 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 coverage is 67% and the undocumented parameter is the required job_handle, which the description never explains. It does add real context for address_confirmed by describing the ADDRESS_UNVERIFIED flow it responds to, and buyer_email is documented in the schema already. Net: baseline 3, since the description neither compensates for the job_handle gap nor repeats 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?

States a specific verb and resource ('Resolve the EXACT amount HIP will charge') and immediately scopes it negatively ('This does NOT charge anything'). It explicitly distinguishes itself from the sibling hip_quote ('hip_quote alone is not the payable amount'), so an agent can route correctly without opening either 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 an explicit when-to-use condition ('paying autonomously with a delegated payment authorization') and an explicit when-not ('a human paying in a browser does not need it'). It also names the recovery path for the ADDRESS_UNVERIFIED error (hip_update_job), routing the agent to the right sibling in the failure case.

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