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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is fully covered. The description adds the aggregate/scope nature and the optional state filter, but does not disclose return shape, default year window behavior, or data vintage. Adds some value over annotations but not rich context.

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 short sentences, front-loaded with what it returns before the usage hint. The final sentence is slightly soft ('Useful for...') but earns its place as a routing cue. Minimal waste.

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 2-parameter, no-output-schema aggregate tool whose safety profile is carried by annotations, the description covers what the tool returns and its scope. It could say more about which financial aggregates are included, but nothing critical to correct invocation is missing.

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% — 'limit' (number of years, default 20) and 'state' (two-letter code) are both fully documented in the schema. The description restates the state filter ('optionally filtered to a single state') but adds no syntax or format detail beyond the schema, so 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?

The description gives a specific verb+resource ('Returns year-by-year aggregates across all FDIC-insured institutions') and states the aggregation scope, which implicitly distinguishes it from institution-level siblings like fdic_financials or fdic_search_institutions. It stops short of explicitly naming the sibling it contrasts with, so an agent must infer the distinction.

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?

'Useful for macro banking-sector analysis' implies when to reach for it, but there is no explicit when-to-use versus alternatives (e.g., use fdic_financials for a single bank, this for the whole sector). Usage is only implied, not directed.

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