post_invoice

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

With no annotations provided, the description carries the full burden and delivers richly: it discloses that entries cannot be added after posting, that exchange rates are etched at posting and cannot be updated retroactively, and that forced stale rates are recorded in the response and audit log as fx_stale/'forced'. The 90-day staleness cap boundary is also disclosed. This is exemplary behavior disclosure for a mutation tool.

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 description is front-loaded with the core purpose in the first line, followed by behavioral notes, then a clean Args block. It's slightly long but every section earns its place given the complex FX-guard behavior. The stale-FX paragraph is dense but necessary; the Args block is well-formatted. A minor deduction for length, but structure is exemplary.

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?

This is a complex 7-parameter mutation tool with no annotations and 0% schema coverage, yet the description thoroughly documents the post-conditions (A/R or A/P transaction, immutable entries), the FX edge-case with its full resolution flow, and every parameter. An output schema exists so return-value explanation is appropriately omitted. For its complexity, it is essentially complete.

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% (no param documentation in the JSON schema), so the description is the sole source of parameter meaning. The Args block annotates all 7 parameters with types, examples ('000001', 'Assets:Accounts Receivable'), defaults, and one optionality note. It adds real semantics for owner_type (disambiguation when IDs collide) and force (override behavior) that the bare schema titles don't convey.

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 states a specific verb+resource ('Post a customer invoice or vendor bill') and explains the consequence (creates a transaction in A/R or A/P, makes the invoice official). It clearly distinguishes from the create_* tools and unpost_invoice sibling, establishing what makes posting unique.

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?

The description explicitly explains when posting is refused (stale_fx_rate beyond GNUCASH_FX_GUARD_DAYS) and precisely the steps to resolve it: run create_price, retry, or pass force=True. It names the sibling tool create_price directly and documents the 7-day vs 90-day staleness boundaries, giving clear alternative paths. The owner_type disambiguation guidance is also useful for post-date error conditions.

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