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

Beyond the read-only and idempotent annotations, the description discloses crucial operational traits: plan gating ('Starter plan or higher', 'Pro plan or higher' for search), credit costs per action, the fact that list/get/search are charged even when nothing matches, and the history window limit. These are exactly the kind of behavioral details an agent needs before invoking a paid read tool.

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 description is organized as a short intro followed by a bullet per action, which is front-loaded and easy to scan. It is slightly dense but every sentence carries meaningful information about cost, plan, or behavior; there is no padding.

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 multi-action paid data-retrieval tool with no output schema, the description covers everything an agent needs: what each action returns ('ids, dates and Items', 'sections, amendment history, original text and attachments'), pagination behavior, credit costs, plan prerequisites, and not-found billing rules. Nothing critical is omitted.

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 schema already documents all 17 parameters well. The description adds value by explaining the required 'action' enum in detail—each action's behavior, cost, and plan requirement—which the schema defers to ('each action is described in the tool description'). It does not add syntax details for other parameters, but it doesn't need to.

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 opens with a specific resource ('Corporate events US companies report to the SEC') and then enumerates the four actions available (types, list, get, search) with their exact scope, so the agent can immediately distinguish this from sibling tools. The Form 8-K framing and Section-per-Item explanation make the purpose unmistakable.

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?

Each action is given a clear role: 'list' is one company's filings, 'search' is across companies by Items and dates, 'get' is one filing by id, and 'types' enumerates Item codes. The description does not explicitly say 'use search instead of list when…' but the action distinctions and plan/price notes make the correct choice sufficiently clear.

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