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

Annotations already declare readOnlyHint=false, indicating a write operation, and destructiveHint=false, so the description does not need to restate mutation. The description adds the list of account types, which is more purpose-related than behavioral. It does not disclose any side effects, permission requirements, or operational constraints (e.g., idempotency, rate limits), so the added behavioral context is thin but not contradictory.

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 a single sentence that front-loads the action ('Creates an account') and then lists the allowed types. It is concise and free of fluff, though the enumeration makes it somewhat long. Still, every word contributes to the purpose, so it is efficient and appropriately sized.

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 nine parameters and many optional fields having specific formats (e.g., last4 regex, maturesOn date, currency ISO code), the description provides no guidance on when each parameter is applicable or required. For instance, it does not explain that 'annualRatePercent' is only for interest-bearing accounts, or what 'last4' refers to. While an output schema exists, the input parameter usage remains unclear, leaving agents to guess about conditional fields and business rules.

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 only 44%, leaving five parameters (name, last4, maturesOn, institution, and kind's meaning) undocumented in the schema. The description only clarifies the 'kind' parameter via the account type list; it provides no guidance on the purpose or format of 'last4', 'maturesOn', 'institution', or the interplay of fields like 'annualRatePercent' with specific account kinds. Thus, it fails to compensate for the low schema coverage.

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 (creates) and the resource (account), and enumerates the specific account types (cash, card, bank, deposit, savings, credit, investment, e-wallet) that map directly to the 'kind' enum. This distinguishes it from sibling tools like list_accounts, update_account, and delete_account. The only minor gap is not mentioning 'other' as a kind, but that does not undermine clarity.

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 name and description—use this when creating an account—but there is no explicit guidance on when not to use it or how it compares to other creation tools like create_budget or create_category. The description does not mention alternatives or exclusions, leaving the agent to infer from the tool name alone.

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