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

Annotations already declare readOnlyHint/idempotentHint, but the description adds the substantive guarantee 'Records nothing' and describes what the response contains (control totals, unmapped accounts, first N rows). That is real behavioral context beyond the structured fields, though it says nothing about size limits or what happens when the period has unmapped accounts.

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 short sentences, front-loaded with what the tool returns and the no-write guarantee before the routing instruction. Slightly awkward register ('The journal for a period in the ledger's shape') costs a point but nothing is filler.

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 return-value burden and does so by naming control totals, sample rows and unmapped items. For a 5-parameter read/preview tool that is largely sufficient; a note on how unmapped accounts affect usability of the preview would close the last 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 every parameter (to, from, rows, format, currency) is already documented, including the omit-'from'-to-resume behavior. The description restates that resume rule rather than adding new meaning, 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 specific operation: produce the journal for a period rendered in the target ledger's shape (xero/qbo/csv), plus control totals and unmapped items. The naming of bridge_export as the follow-on action implicitly distinguishes it from the export sibling. Slightly indirect phrasing ('the ledger's shape') but an agent can tell what it gets back.

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?

Explicit sequencing: 'Show the person the totals and the first rows before bridge_export' tells the agent this is a pre-flight step, not the hand-over itself. It also explains the omitted-'from' case (resume from the last hand-over in that format). It doesn't address other near siblings such as bridge_journal or bridge_financials, so 4 rather than 5.

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