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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds valuable non-annotation behavior: results are returned most-recent first, and the event-type scope is made explicit. It could disclose pagination or how the default limit is applied, but for a read-only timeline lookup the disclosure is solid.

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 with zero filler: the first delivers resource, scope, and event types; the second delivers ordering. The most important constraint (by CERT) is front-loaded. Every phrase earns its place.

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 lookup with one required parameter, no output schema, and annotations covering safety, the description is nearly complete: an agent knows the key, the optional limit (via schema), the event types, and the ordering. Minor gaps remain, such as the return shape or behavior when a CERT has no events, but nothing that would block a correct call.

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 the schema already documents both cert and limit, establishing a baseline of 3. The description adds marginal context by highlighting cert as the key and noting the event types that limit caps, but doesn't contribute meaningful parameter-level 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?

The description names the specific resource ('institution history events for a specific bank by CERT') and enumerates the exact event types included (mergers, acquisitions, name changes, charter conversions, failures), plus the result ordering. This clearly differentiates it from FDIC siblings like fdic_failures (failure lists) or fdic_search_institutions (institution lookup), even though the verb is implied rather than stated.

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 phrase 'for a specific bank by CERT' implies the tool is for when an agent already knows a bank's certificate number and needs its event timeline. However, it never names alternatives such as fdic_failures or fdic_search_institutions, nor states when not to use this tool, leaving routing among the many FDIC siblings to inference.

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