iban_validate

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 well: it discloses what is computed, which countries get enrichment (DE, AT, CH, NL, BE, LU, LI), and gives cost ($0.0025 USDC/call) and p99 latency (1500ms) — useful operational context rarely stated elsewhere. It stops short of describing failure behavior for an invalid IBAN or any auth/rate-limit details, so it is strong but not exhaustive.

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?

A single dense sentence front-loads the validation scope before the enrichment clauses, and the trailing cost/latency note is compact and actionable. Nothing is redundant, though the sentence is long enough that the enrichment detail slightly crowds the core purpose.

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 and no annotations, the description compensates by naming the returned fields (bank code, branch, account number, SEPA flag, bank name/BIC/city for supported countries), which is exactly what an agent needs to call it correctly. Error/edge-case behavior is the one notable omission.

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?

The schema already documents the single parameter at 100% coverage ("IBAN, spaces allowed"), and the description merely restates it as "iban (required, spaces allowed)" with no format examples, country-length constraints, or normalization rules added. Baseline 3 is appropriate when the schema does all the work.

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 (validate) and resource (IBAN) and enumerates exactly what validation covers: checksum, country length, structure, split into bank code/branch/account, SEPA membership, plus country-specific enrichment for seven countries. An agent can distinguish this from the many other *_validate siblings (vat_validate, email_validate, phone_validate) purely from the text.

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?

Usage is implied by the resource name — use it when you have an IBAN to check — but there is no explicit when-to-use/when-not-to-use statement and no routing to or away from sibling validators. Adequate but leaves the agent to infer the calling context.

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