get_customer_vault_record

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

With no annotations provided, the description carries the full burden. It explicitly discloses 'Read-only' and adds a critical safety detail: 'Returns stored profile data only — never full card numbers.' This goes beyond a mere fetch statement, though it does not mention error behavior or auth requirements, which are minor for a read operation.

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 sentences, front-loaded with the core action, followed by useful privacy and safety context ('never full card numbers') and a clear 'Read-only' declaration. Every word earns its place; no filler or redundancy.

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 simple one-parameter read-only tool without an output schema, the description explains the tool's scope (single record), the expected input (customer_vault_id), and key behavioral constraints (read-only, no full card numbers). It is sufficient for an agent to invoke correctly, though it omits potential edge cases like 'not found' responses, which are not essential for basic usage.

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%: the parameter 'customer_vault_id' is fully described as 'The Customer Vault ID to look up.' The description repeats the parameter name but adds no extra semantic detail (e.g., format, length constraints beyond minLength). Baseline 3 is appropriate because the schema already handles parameter meaning.

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?

The description clearly states the action ('Fetch a single stored Customer Vault record'), the resource ('Customer Vault record'), and the key identifier ('customer_vault_id'). It also disambiguates from sibling tools like list_customer_vault by specifying 'single', and from get_transaction/get_subscription by naming the vault-specific report_type.

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 phrase 'by its customer_vault_id' makes clear this tool is for looking up a specific vault record when the ID is known, providing implied usage context. It does not explicitly name alternatives or exclusions, but the presence of sibling list tools suggests the contrast is unnecessary for this simple read-only fetch.

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