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

Adds substantial context beyond readOnlyHint=false: it discloses that this writes stored state, is 'not safe to repeat blindly', creates no liability and moves no money, and that it refuses when there is no recorded payment to bind. The authorization scope and the refusal behavior are exactly the traits an agent needs before invoking a mutation.

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?

Purpose is front-loaded in the first clause, followed by the gap scenario, authorization, and the write warning. The middle sentence is a dense run-on, but every clause carries information an agent needs; little is padding.

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 2-parameter mutation with no output schema and only a readOnlyHint annotation, the description covers the behavioral and authorization picture well. The remaining hole is parameter meaning, especially the unexplained `secret`, which leaves the definition slightly incomplete for invocation.

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 0% and the description explains neither parameter. `award_id` is inferable from the name, but `secret` (an optional string) is entirely undocumented in both schema and description, leaving the agent guessing at its role. With low schema coverage, the description should compensate and does not.

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 ('Close an award against a payment that was ALREADY recorded') and immediately distinguishes itself from the normal path ('Settlement normally happens inside the receipt write'), which separates it from siblings like mark_award_payable and payout_receipt. The agent knows exactly what state transition this performs.

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 a precise triggering condition: the receipt was recorded before the award was decided, leaving an award reading payable. It also names the authorized callers (the payee the award names or the funder of its listing). It stops short of explicitly naming an alternative tool by name, but the 'gap' framing is clear enough to route correctly.

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