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

Annotations only declare the safety profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false); the description goes further by disclosing that the tool returns a receipt (row count, period, location) and never the rows, and explains why. That preempts the common failure mode of an agent expecting inline data and re-querying.

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, front-loaded with the action and the delivery mechanism, then the return contract, then the routing rule. The clause about duplicating data and worsening answers is slightly padded, but it earns its place by justifying the no-rows behavior.

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 an output schema present, return values need not be explained, yet the description still summarizes the receipt shape. Scope, delivery mechanism, and the sibling routing rule are all covered, and nothing an agent needs to invoke it correctly is missing.

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 optional with documented ISO-date semantics and defaults, so the schema carries the parameter burden. The description adds no date-syntax or boundary detail beyond it, making the baseline 3 correct.

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?

Specific verb (write/export) plus resource (household transactions for a period) plus target format (CSV downloadable from the Truo portal). It also explicitly carves itself out from list_transactions, so an agent can distinguish the two without opening schemas.

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 crisp decision rule: use list_transactions when the question is 'which ones', use this when the answer is 'give me the file'. That is an explicit when-to-use plus a named alternative, which is the top of the scale.

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