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

With no annotations, the description carries the full burden and does so: it discloses that the operation is terminal ('409 HOLD_NOT_ACTIVE if already settled'), that the uncaptured remainder returns to the holder, that the recipient may be created if new, and that it costs 1 CRD even when rejected while a 429 is free. It also lists the specific error codes and tells the agent to quote request_id to support, which is unusually complete behavioral disclosure for an irreversible settlement.

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?

Every sentence carries load: settlement outcome first, then the amount/remainder rule, then recipient routing, then failure codes, then cost model, then support guidance. No repetition of the tool name and no filler, despite the density of parenthetical detail.

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 9-parameter mutation tool with no annotations and no output schema, the description covers side effects, cost, failure modes, and the destination of captured credits. The main residual gap is the shape of a successful response (aside from the request_id on errors), which an agent must discover on its own.

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 78%, so the baseline is 3, and the description earns above that by clarifying that amount defaults to the full hold and that the residual flows back to the holder, plus that to_user_id/to_user_email route captured credits to a possibly-new recipient. It adds nothing about reason, metadata, or when x402_payment is required (the schema covers api_key and project_id).

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?

The description opens with a specific verb+resource ('Settle a hold') and immediately pins down the resulting state ('status captured'), which is enough to separate it from release_escrow_hold or list_escrow_holds. It never names those siblings explicitly, so an agent must infer the boundary from the settle-vs-release wording rather than being routed.

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?

It spells out the two operating modes and the condition that selects each: pass to_user_id/to_user_email for marketplace/P2P settlement, omit them and the capture 'stays deducted (settled to the platform).' That is clear usage context, but there is no exclusion or alternative named (e.g. when to release instead of capture).

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