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

Annotations already cover readOnly, idempotent, openWorld and non-destructive, so the description doesn't need to restate safety. It adds useful context beyond them: keyless access, the active-plan constraint, and the shape of returned records (EIN, effective date, participant count).

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 the scope constraint first, then return fields, then usage examples. The two example calls are slightly redundant for a 6-param tool but each demonstrates a different filter pattern, so they earn their space.

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?

No output schema exists, and the description compensates by listing the returned fields. Combined with full schema coverage and annotation-declared read semantics, an agent has everything needed to call this 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 the baseline is 3, but the two call examples demonstrate realistic parameter combinations (sponsor-only, and state+plan_type+limit), showing how filters compose. That adds meaning beyond the field descriptions without over-explaining.

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 and resource: 'search plans currently paying PBGC premiums', with an explicit negative scope ('NOT terminated/trusteed') that separates it from the sibling pbgc_search_trusteed_plans. It also enumerates the returned fields, so an agent knows exactly what it gets.

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 active vs terminated/trusteed distinction gives clear selection context, and the sample natural-language questions show when to reach for it. It doesn't explicitly name pbgc_search_trusteed_plans as the alternative, so the routing is inferable rather than stated.

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