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

With no annotations, the description carries the full burden and does so: it defines PASSED only for NORMAL status, states dissolved/liquidated/unknown FAIL, and that source uncertainty returns UNAVAILABLE rather than a pass. It also discloses quota and cost behavior — 1 free attempt per UTC day per IP shared across REST/MCP with failures counted, then 0.01 USDC with explicit approval.

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 core action and the PASS/FAIL rule, then alternatives, then pricing. Every sentence carries information, though the pricing/quota sentence and the alternative list make it denser than ideal for a single-parameter lookup.

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?

Complete for a simple lookup: it covers the input requirement, the three possible outcome states, the returned value (registered name), failure semantics, and cost/quota. No output schema exists, but the description already explains what comes back, so nothing material 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 coverage is 100% and the single parameter is already well documented in the schema, so the baseline is met. The description adds selection-level meaning by warning that this is a CRO number, not a company name or VAT number, reinforcing the schema's negative guidance without adding new format rules.

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?

Names a specific verb and resource: looks up an Irish company by CRO number in the Companies Registration Office open data, and states the outcome (registered name). It also implicitly distinguishes itself from name/VAT lookups, so an agent can tell it apart from check_vat and the supplier-payment siblings.

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 says to supply a CRO number rather than a company name or VAT number, and routes the agent to named alternatives with their conditions: check_vat for VIES, verify_supplier_payment for identity reconciliation, decide_supplier_payment for a full invoice decision. It also states the boundary 'No invoice is approved here.'

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