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

The annotations already declare readOnly/idempotent/non-destructive, so the description only needs to add context, and it does: both registers are searched, results carry data_as_of so freshness is visible, and no key is required. It does not describe the shape of a match record or how multiple matches are ordered or capped, though the limit parameter's schema covers that.

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?

The core purpose and outcome taxonomy come first, which is good front-loading, and the example questions are useful. But the inline example call duplicates the schema's examples array, and three sample questions are one more than needed.

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?

There is no output schema, so the description must explain the return: it names the match fields implicitly (status, data_as_of) and sets expectations about currency. It never says what a record contains beyond that, which is the main remaining gap for a search tool.

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?

With 100% schema description coverage, the baseline is 3. The description restates the searchable fields (sponsor, plan name, EIN) and implies they can be combined with 'and/or', which adds a little beyond the schema, but limit behavior and the exact-match vs. partial-match distinction for EIN are left to 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 gives a precise verb and resource: look up a named plan sponsor's PBGC status, and it defines the two possible outcomes (trusteed/terminated vs. active premium-paying plan). It also distinguishes the tool's scope by stating it searches both PBGC registers, which separates it from the sibling tools pbgc_search_trusteed_plans and pbgc_search_premium_filers.

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?

Three example questions make the intended use concrete, and 'Keyless' answers the auth question an agent would otherwise have to test. It does not, however, name a sibling or state when another tool would be a better choice, for example, an industry-total or premium-filer lookup.

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