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

Annotations already declare readOnlyHint=true and destructiveHint=false, indicating a safe read operation. The description adds the return fields, which is useful context, but it does not disclose any other behavioral aspects like error handling, permissions, or rate limits. This is consistent with annotations, and the description adds moderate value beyond the structured hints.

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 is concise and front-loaded with the primary action. It contains no superfluous content and communicates the purpose and output efficiently.

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 fetch-by-ID tool with read-only annotations and a fully described schema, the description covers the purpose and output fields, which is sufficient. It could mention error behavior (e.g., what happens if the account is not found), but that is not critical for a read operation and the schema already covers parameter requirements.

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?

The schema provides 100% coverage of both parameters, with descriptions for accountId (from list_accounts) and householdId (with conditions for omission). The description text adds no additional parameter semantics, so the baseline of 3 applies because the schema already documents the parameters adequately.

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 tool fetches a single financial account by ULID, with a specific verb ('Fetch') and resource ('financial account'), and lists the returned fields (name, type, currency, balance, status). This distinguishes it from list_accounts and other getters like get_budget or get_payee, which operate on different resources.

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 provides no explicit guidance on when to use this tool versus alternatives. It does not mention that list_accounts should be called first or that this tool is for retrieving a specific account after listing. The only hint comes from the schema's accountId description ('from list_accounts'), which is not part of the description text.

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