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

Annotations already declare readOnly/idempotent/non-destructive, and the description goes well past that: it says nothing is posted or stored, re-derivation is the truth, accounts are fixed, voided invoices are excluded (INV-23), and the ledger of record owns inventory and margin. That is exactly the kind of derivation and side-effect disclosure an agent needs to reason about repeat calls and downstream reconciliation.

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?

Front-loaded with the core statement (what it produces and who consumes it), then qualification sentences. The closing line 'The ledger of record stays wherever it is' largely restates the earlier ownership point and could be cut, but otherwise the prose is dense and purposeful.

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?

With no output schema, the description carries the burden of explaining the result, and it does so at the level of content (revenue-side lines, fixed accounts, no COGS) rather than row shape. For a three-optional-parameter read tool with full safety annotations, that is nearly complete; a note on what a single journal line contains would close the gap.

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 100%, so to/from/currency are already fully documented in the schema, including the ISO formats and the currency-summing caveat. The description adds no additional parameter semantics beyond that, so the baseline 3 applies.

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 concrete resource (double-entry journal lines derived from the books) and the intended consumer (export to the ledger of record). It does not name or distinguish itself from the plausible lookalikes in the sibling list (gl_entries, gl_changes, bridge_export), so an agent must infer the boundary rather than read it.

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?

Usage is implied through scope statements — revenue side only, no COGS/inventory, voided invoices contribute nothing — which effectively describes what the output will and will not contain. However there is no explicit guidance on when to choose this over gl_entries or bridge_export, and no stated prerequisites such as needing books to exist first.

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