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

Adds real value beyond the readOnly/non-destructive annotations: it discloses the privacy posture of the blind registry and explicitly enumerates the only fields returned, including negative guarantees ('never returns lender identity or invoice details'). It does not explain token-vs-fields precedence or what happens if both are supplied.

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 tight sentences: purpose first, accepted inputs second, return contract third. No redundant restatement of the name or title and nothing that fails to earn its place.

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 no output schema, the description correctly compensates by listing the returned fields and their limits, which is what an agent needs to interpret the result. The only remaining gap is validation behavior for partial or mixed input modes.

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%, so the baseline is 3; the description earns an extra point by clarifying that the token is an alternative path to the five field parameters rather than an additional filter, a relationship the schema alone does not make explicit. It still does not say which fields are mandatory when the field-mode is chosen (required parameters list is empty).

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 ('Check whether an invoice has already been financed') plus the scope ('on the blind registry'), so there is no ambiguity about what the call does. It does not explicitly name the sibling write paths (register_financed_invoice / release_financed_invoice), so sibling differentiation is left implicit.

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 concrete invocation guidance by naming the two accepted input modes: the five invoice fields, or a token. It does not state when to prefer this over alternatives such as read_package or screen_sanctions, so context is clear but exclusions are absent.

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