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

Goes well beyond the annotations: discloses that the number lands in a secret store, only the last four are recorded and returned, it must be passed once and not repeated, PERMISSION_DENIED is returned on submitted applications, and ABORTED means a concurrent change and safe retry. This is a rich behavioral contract not derivable from destructiveHint/openWorldHint.

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 action and eligibility, then prerequisite, then behavioral/error semantics. Every sentence conveys necessary operational detail with no filler.

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?

For a mutating, secret-bearing tool with auth/submission constraints, the description covers eligibility, prerequisite ordering, privacy handling, and both key error codes. Output schema exists so return format needn't be fully explained, and the last-four note is a useful bonus.

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 67% with wrapper descriptions for the UUID ids. The description meaningfully expands documentNumber's semantics (secret storage, last-four return, single-use) though it adds little about applicationId/ownerId beyond the schema. Good value over structured data.

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 (files) and resource (identity document number) scoped to a beneficial owner with no SSN/ITIN, which implicitly distinguishes it from banking_set_owner_tax_identifier. An agent can tell exactly what this does without opening the schema.

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?

Explicit eligibility condition (owner lacks SSN/ITIN), prerequisite ordering (record the document kind/country/expiry/state first), retry guidance for ABORTED, and exclusion for already-submitted applications. Covers when, when-not, and alternatives implicitly.

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