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

Adds substantial behavioral context beyond the annotations: exact charge semantics ('charges exactly that total and never more'), the security constraint ('NEVER send a card number, expiry, CVV or any reusable credential'), and the failure mode ('returns payment_status=requires_user_action rather than bypassing' authentication). This goes well past destructiveHint/idempotentHint.

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?

Four sentences, all front-loaded and earning their place: purpose, token requirement, security prohibition, edge case. Slightly dense, but no filler or repetition.

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 two-param mutation tool with no output schema, the description covers the money-flow contract, token requirements, credential prohibition, and the requires_user_action outcome. It omits what job_handle is beyond the name and doesn't state idempotency/retry behavior, both of which matter for a non-idempotent, destructive operation.

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 only 50% (job_handle has no description), but the description compensates by fully qualifying payment_authorization: format (spt_...), issuance constraint (granted to Have It Printed), and range constraint (max ≥ total). job_handle remains undocumented anywhere, so not a full 5.

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 ('pay for the job') with the mechanism ('delegated payment authorization, no browser, no human step'), which distinguishes it from siblings like hip_prepare_payment (prepares total) and hip_create_checkout (browser checkout). An agent can route correctly from the first sentence.

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?

Provides a clear precondition (token must be an spt_ granted to Have It Printed with a max at least the total from hip_prepare_payment) and a natural pairing with hip_prepare_payment. It doesn't explicitly say when NOT to use this vs. hip_create_checkout, but the 'no browser, no human step' framing implies the distinction.

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