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

Beyond the annotations (readOnly, idempotent), the description discloses critical context: the `{ results, errors }` batch shape, the potential `provider_incident` block, and a clear warning that values may be unreliable during provider incidents and should not be presented as real. This adds significant value beyond structured annotations.

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?

The description is compact and front-loaded with the main return value, followed by usage and a caveat. Every sentence contributes; the provider incident explanation is somewhat detailed but necessary for safe use.

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 one-parameter read tool with no output schema, the description is remarkably complete: it specifies the endpoint, batch shape, response envelope, and a critical edge case (provider incidents). It leaves little ambiguity about what to expect.

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 0%, so the description carries the burden. It explicitly states to pass `account_ids` as an array with a 1–50 limit, adding meaning beyond the bare schema. It does not detail each element's type beyond implicit ID, but that's sufficient for the single parameter.

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 explicitly states 'Returns full account objects including extended creditData (additional cards, limits) per id', a specific verb+resource that clearly distinguishes from siblings like list_accounts or get_account_balance. The batch shape and per-id behavior further define its purpose.

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 description gives clear context: use when you need full account details for specific IDs, with the instruction to pass account_ids as an array (1–50). It does not explicitly name alternatives or exclusions, but the sibling set and the phrase 'full account objects... per id' imply when this is appropriate.

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