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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so the safety profile is covered. The description adds genuine behavioral context beyond that: results are 'live', and the response can be partial, carrying a `warnings` array with per-bank messages and a reconnect_url — a detail that changes how an agent should interpret and act on the output.

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, zero filler. The core action and scope lead, and the response-shape sentence follows because no output schema exists to carry it.

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 one required parameter, rich annotations, and no output schema, the description does the necessary lifting by outlining the returned fields and the warnings/reconnect mechanism. The remaining gap is error semantics — what happens when the account_id is unknown or stale — which is not addressed.

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% and the single account_id parameter is already documented with an example in the schema. The description only restates the provenance ('by its account id from list_accounts'), adding no new format or validation detail beyond the schema.

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?

Specific verb ('Get') plus a precisely scoped resource ('one account's live details') with the returned fields enumerated (balances, credit limit, type, institution, last 4 digits). It also names the source of the identifier ('from list_accounts'), which cleanly separates it from the list_accounts sibling.

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 establishes the prerequisite workflow by stating the account id comes from list_accounts, so an agent knows to enumerate first and then fetch details. It does not state exclusions or compare against sibling alternatives (e.g. list_holdings for investment data), but none of the siblings is a real substitute for single-account detail.

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