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

Goes well beyond the annotations: it discloses that the tool holds no key and takes no payment, that the external door settles and only a verified settlement marks a packet funded, that closed claim lanes are refused before any challenge, and that the call is not safely repeatable on timeout. The duplicate-payment warning is exactly the context the idempotentHint=false annotation cannot convey on its own.

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?

The core action and required inputs are front-loaded in the first sentence, and each subsequent sentence covers a distinct concern (forwarding, settlement, refusal, timeout). The closing cost/signer sentence restates ground already covered earlier ('holds no key, takes no payment'), costing some tightness.

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?

An output schema already exists, so return values need no explanation; the description instead covers the paths an agent cannot infer — missing xPayment, closed claim lane, door timeout, and who signs and pays. Nothing needed to call this 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?

Schema coverage is 100% and each parameter already documents itself, including the accepts[] linkage and the address-only rule. The description reinforces the order dependency on prepare_funding but adds little syntax or format detail beyond the schema, so the baseline 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 and resource ('Finish funding a packet from your own wallet') and immediately names the three required inputs. It distinguishes itself from the preparation sibling by requiring an already-signed xPayment built against prepare_funding's challenge, so an agent can tell it apart from prepare_funding and the other submit_* tools.

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 explicit sequencing (call after prepare_funding), explicit failure routing ('Without xPayment it refuses and points you back to prepare_funding'), and explicit when-not-to-retry guidance ('If the door times out, do NOT pay again: read work_status first'). Alternatives and the conditions selecting them are named, not inferred.

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