invoices_validate

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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds value beyond that by disclosing the return content ("list of errors and warnings") and the cost tradeoff between modes (fast vs. slower comprehensive checks), which is not in the annotations.

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 with zero filler: purpose first, return value second, mode selection last. All actionable information is front-loaded.

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?

For a read-only validation tool with no output schema, the description covers purpose, inputs (via schema), mode behavior, and the shape of the result (errors and warnings). It could go slightly further on whether a failed validation errors out versus always returning a report, but the essentials are present.

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 coverage is 100% and every parameter, including the mode enum and the companyId override fallback, is already documented in the schema. The description's mode explanation largely restates the enum description, so it adds little beyond structured data. Baseline 3 is appropriate.

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+resource ("Validate an invoice") with an explicit scope qualifier ("before issuing or submitting") that separates it from the write siblings invoices_issue and invoices_submit. An agent can identify the tool's role without opening the schema.

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 clear when-to-use condition ("before issuing or submitting") and explains the choice between the two modes ("quick" for fast basic rules, "full" for comprehensive compliance). It does not explicitly name or exclude alternatives, but the workflow positioning is unambiguous.

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