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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false), so the description's contribution is the output-shape disclosure: it returns a receipt (row count, period, location) and deliberately never the rows. That is genuine behavioral context beyond the schema. It does not mention idempotency or what happens on repeated exports, so it falls short of a 5.

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 action, the delivery, and the sibling routing, so the key facts come first. It is somewhat long-winded in justifying why rows are not returned, but that sentence earns part of its place by preventing a misuse pattern.

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?

A two-parameter export tool with an output schema, full schema coverage, and annotations supplying the safety profile. The description nonetheless adds the one thing structured fields do not convey: that the answer is a file plus receipt, not rows.

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% and both parameters are fully documented with their defaults, so the baseline is 3. The description only restates 'for a period' without adding date syntax or boundary behavior beyond the schema.

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 ('Write the household's transactions for a period to a Excel file') and adds the delivery mechanism (download from the Truo portal). It is easy to distinguish from list_transactions, export_transactions_csv, and export_statements_xlsx.

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?

Explicitly routes the agent: 'Use list_transactions when the question is "which ones" and this when the answer is "give me the file".' That is a concrete when-to-use/when-not rule naming the alternative. The only minor omission is not differentiating from export_transactions_csv or export_statements_xlsx.

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