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

Annotations only declare readOnlyHint and openWorldHint; the description adds substantial non-annotation context: metered pricing at $0.002 USDC per successful call, x402 payment paths, and the fact that failed calls are not charged — material for an agent deciding whether to call. It omits any note on rate limits, caching, or result-set paging behavior.

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?

Three compact sentences, front-loaded with what the tool returns, followed by the scope exclusion and then the cost. No filler, no restatement of the title, and the commercial terms are placed last where they belong.

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?

An output schema exists, so field-level return description is not strictly needed, yet listing the fields still helps an agent judge relevance at a glance. Combined with the payment disclosure, the only real gap is the absence of any statement on paging/limits interaction or expected result volume for a state query.

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%, so both parameters (state, limit) are already fully documented including the 1–50 range and default. The description only reinforces the single-state scoping constraint and adds no format or syntax detail beyond the schema; baseline 3 applies.

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?

States a specific resource (FDIC-insured bank institutions), a specific scope (one US state), the data source (FDIC BankFind API), and enumerates the returned fields (name, certificate number, address, ZIP, charter class, active status). The FDIC/BankFind framing distinguishes it from the sibling finance_ffiec_bank_institutions without the agent needing to open a schema.

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?

"Institution data only; no financial statements" is an explicit when-not boundary, and "one US state" clarifies the query model. It does not name an alternative tool (e.g. the FFIEC sibling) for callers who actually want financial statements, so routing is left partly to inference.

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