validate_invoice_sg

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

With no annotations provided, the description carries the full transparency burden. It discloses the tool's limited validation depth, a concrete rejection example (missing buyer/seller UEN), the non-included rulesets, a warning that will appear in results, the rationale, and the optional xslt2 dependency.

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?

The description is purpose-first and separated into clear blocks, but the second paragraph becomes dense with implementation references such as validators/schematron.py, a roadmap file, and a ticket ID. These details add noise for an agent whose main job is selecting and invoking the tool correctly.

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?

Given a single required parameter, no annotations, and an available output schema, the description supplies everything needed: input format, validation target, limitations, expected warning behavior, and installation prerequisite. The agent can call the tool without needing further clarification.

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 the single xml parameter is already documented as the UBL 2.1 XML invoice content to validate. The tool description adds surrounding context but no material parameter-level meaning beyond what the schema already provides.

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?

The first sentence states a specific verb and resource: validate a UBL 2.1 XML invoice against IRAS's C5 acceptance-layer Schematron. It is further differentiated from sibling tools by naming the exact ruleset scope and what is not included.

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?

The description explicitly states when to use the tool (for C5 acceptance-layer checks) and, more importantly, when not to rely on it for full compliance by listing the EN16931 base ruleset, PINT-SG overlay, and SG Peppol BIS Billing 3.0 as not checked. It also directs the caller to the EN16931-BASE-UNAVAILABLE warning in the result.

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