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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds useful context by listing returned fields and noting the tool is keyless, which informs authentication expectations, but it does not discuss rate limits or result-set completeness.

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-loads the purpose, then lists return fields, sample questions, and compact example calls. Every sentence contributes useful context with no filler.

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, but the description explicitly enumerates the returned fields, including case number, sponsor, plan name, EIN, termination date, trusteeship date, and participant count. Together with full schema coverage and annotations, this gives an agent enough to call the tool 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 description coverage is 100%, so all six parameters are already documented in the input schema. The description provides example invocations using sponsor, state, and limit, but adds little semantic detail beyond what the schema supplies, consistent with the baseline 3 when the schema does the heavy lifting.

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 verb and resource: searching PBGC's register of single-employer pension plans that PBGC has trusteed, with a clear definition of 'trusteed.' This distinguishes it from sibling PBGC tools such as pbgc_plan_status and pbgc_search_premium_filers by focusing specifically on taken-over plans.

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?

Provides clear usage context via example questions ('pension plans PBGC has taken over in Illinois', 'list trusteed plans for United Airlines') and sample invocations with sponsor, state, and limit. It does not explicitly say when not to use this tool or name the sibling tools to use instead, 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.