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

Annotations only declare readOnlyHint, so the description carries most of the burden and delivers: units (asset/dep in thousands), an ACTIVE-ONLY store with the merge/fail consequence, the DATA_UNAVAILABLE refusal on an unreachable store, and the `ticker` attribution caveat. This is exactly the behavioral context annotations cannot supply.

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?

Front-loaded with purpose and return shape, then units, store scope, error state, and attribution. Dense and telegraphic but every clause carries information; the ALL-CAPS emphasis aids scanning without adding 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?

With no output schema, the description still describes the return shape ({summary, query?, found?, institutions}), units, active-only scope, error behavior, limit bounds, and source/attribution. An agent has everything needed to call and interpret it correctly.

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 coverage is 100%, so baseline is 3, but the description adds value beyond the schema: `query` is a prefix (not substring) match scoped to active institutions with largest-asset-first ordering, and it reinforces the limit default/cap. Prefix vs substring semantics are genuinely useful.

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 banks and thrifts) and the exact lookup behavior: name-prefix search when `query` is passed, top-by-assets list when omitted. An agent immediately knows this is an FDIC institution lookup, distinct from the structure-events sibling it references.

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?

Explicitly explains the two usage modes (pass `query` for prefix search vs omit for the largest active institutions) and hints at the structure-event angle. It does not name an alternative sibling tool or state when-not-to-use, so it falls short of a 5.

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