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

Annotations already declare readOnlyHint/idempotentHint/openWorldHint, and the description adds real context beyond them: the output is rule-based signals, not a verification of ownership and not escrow or theft protection. That explicitly caps what the agent can claim from a positive result, which is the key behavioral risk here. It does not discuss determinism of the checksum check or coverage gaps in the risk signals, keeping it below 5.

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?

Two short sentences: the operation first, the limitation second. Nothing is repeated from the schema or annotations, and every clause earns 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?

A read-only, three-parameter check with a full-coverage schema and an output schema, so return values need no explanation. The description covers scope and its limitations adequately. Only the absence of routing guidance to the related IBAN and rental tools leaves a small gap.

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% with all three parameters explained, including the ISO 3166-1 alpha-2 example, so the schema carries the semantics. The description only adds the word 'checksum' for the IBAN and the notion of 'supplied' indicators, which is marginal value over the schema. Baseline 3 applies.

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 ('Check') plus the exact inputs being evaluated: the deposit IBAN checksum and the supplied country/viewing indicators. An agent can distinguish it from generic siblings like iban_check because the resource is a rental deposit risk bundle. It stops short of naming a sibling it is not, so it does not reach 5.

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 second sentence sets a clear boundary on what the result means ('Rule-based risk signals only; no ownership verification, escrow protection or guarantee'), which implies when not to rely on it. However, it never says when to choose this over iban_check, rental_listing_risk, or rental_verdict, so routing among near-neighbours is left to inference.

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