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

Annotations already mark it read-only, idempotent, non-destructive, and closed-world, but the description adds crucial behavioral detail beyond them: passing country_iso triggers a per-record eligibility check that attaches `eligible`, `blocking_errors`, and `remediation`. It also enumerates the returned fields, which is valuable since there is no output schema.

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 purpose and return shape, then eligibility behavior, then sibling links. It is dense and slightly list-heavy in the return-field enumeration, but every clause carries actionable information 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?

With no output schema, the description compensates fully by enumerating the returned fields and the conditional eligibility/remediation fields, plus the correct follow-up tools. An agent has everything needed to call and use the result correctly.

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, but the description adds genuine meaning: country_iso is sourced 'straight from a DID's registration_required block' (via buy_did) and requirement_type switches the rule set between regulation and E911 emergency requirements.

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 ('List the authenticated customer's regulation identities with their uploaded proof documents') and immediately scopes it to the caller's account. It is clearly distinguishable from create_identity, update_identity, and delete_identity in the sibling set.

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 states when to pass country_iso/did_group_type and requirement_type 'emergency' for E911, and routes the agent to concrete next tools ('Use an identity id with create_address / update_identity / create_regulation_upload_link. If no suitable identity exists, create one with create_identity').

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