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

Goes well beyond the annotations: it discloses the state change ('a payment that covers the full balance changes the invoice to Paid'), the confirmation default and that it can be switched off, that the action 'reaches other people' requiring user confirmation, and the API-key/access prerequisite. OpenWorldHint only says the tool touches external systems; the description explains the concrete human-impact and auth implications.

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 action and safety-relevant constraints. Slightly repetitive: 'Records an offline payment as Collect Payment does in Jobber' restates the opening sentence without adding much. Otherwise tight and well ordered.

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 mutation tool with no output schema, it covers the key behavioral facts an agent needs: the side effect on invoice status, no card charge, confirmation behavior, and auth requirements. It could say more about what the call returns or error cases, but nothing critical 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?

Schema description coverage is 100%, so invoice_id, amount, method and paid_on are already documented in the schema. The description alludes to payment method types ('cash, check or other offline payment') but adds no syntax, format, or default details beyond the schema. Baseline 3 is appropriate.

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 with scope: 'Record a cash, check or other offline payment against an invoice,' immediately distinguishing it from card-charge payments ('It does not charge a card'). An agent can tell this apart from jobber_create_invoice and jobber_send_invoice without opening a 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 context for when to use it ('offline payment ... as Collect Payment does in Jobber') and implies an exclusion via 'It does not charge a card.' However, it never names an alternative tool for card charges or reconciliation, so the routing guidance is implied rather than explicit.

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