Revise a draft credit note

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

With no annotations, the description carries the full burden, and it delivers the non-obvious traits: draft-only precondition, immutability of finalized notes with refusal behavior, partial-update semantics ('Pass only what changes'), and destructive replacement of lines. It omits permissions/auth requirements and any hint about the error shape when a finalized note is refused.

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?

Three sentences, all load-bearing: what can change, how to send changes, and the guardrail. The mutability precondition is front-loaded and nothing is repeated from the schema verbatim.

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 the behavioral essentials (draft scope, partial update, line replacement, finalized refusal). The unexplained reason_detail parameter and the unnamed sibling for finalization are the only meaningful omissions.

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 only 56%, and the description compensates by naming the mutable fields that lack schema descriptions (recipient, reason, issue date) and by clarifying the partial-update contract. It also reinforces the replace-all-lines rule. It does not explain reason_detail or list the reason enum values, so some gap remains.

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 (change a draft credit note) and enumerates exactly which fields are mutable: recipient, reason, lines, currency, invoice reference, issue date, notes. The 'while it is still a draft' clause cleanly separates it from credit_note_finalize and credit_note_create in the sibling set.

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 clear use condition (only while still a draft) and an explicit exclusion ('A finalized note is immutable and is refused by name'), which routes the agent away from updating finalized notes. It stops short of naming the alternative tool (e.g. credit_note_finalize) for that case, leaving the next step to inference.

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