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

With no annotations, the description carries the full burden. It usefully discloses that the operation is non-blocking ('keeps the ledger honest without blocking') and that negative deltas are legitimate, which tells the agent this call will not fail on overage. It says nothing about idempotency, permissions, or what happens if the handle is stale or invalid.

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?

Two tight sentences with the core semantic (delta against reservation) front-loaded and no filler. The parenthetical is dense but earns its place by defining the sign convention.

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 annotations, no output schema, and 3 of 4 parameters undocumented, the description explains the operation's intent well but leaves the agent guessing about which unit to submit, what 'note' does, and the failure modes. Adequate but with clear gaps.

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 only 25% (only 'handle' is documented), so the description must compensate. It clarifies the sign convention for the numeric inputs — positive when the call cost more, negative to return an overestimate — which is genuinely useful for 'usd'/'tokens', but it never distinguishes when to send 'usd' vs 'tokens' or what 'note' is for, leaving two parameters unexplained.

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 operation: reporting actual usage as a delta against what was reserved, with sign semantics spelled out. This distinguishes it implicitly from 'reserve' (the pre-call step) referenced by 'what you reserved', but it never names a sibling explicitly and the bare name 'record' carries no meaning on its own.

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?

'After a call' gives a clear triggering context and the 'minus what you reserved' phrasing implies the reserve-then-record sequence. However, there is no explicit when-not guidance, no named alternative, and no statement of what to do if no reservation was made.

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