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

Beyond the annotations, the description discloses the price ($0.02), payment asset and network (USDC on Base only), payment protocol (x402 v2), that it returns a 402 rather than performing the check, and important data limitations: quarterly filing cadence, 45-day lag, original 13F-HR only, and possible staleness.

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 payment terms and next step are front-loaded, but the description is long for a zero-parameter quote tool and repeats 'USDC on Base only.' The final legal and non-advice boilerplate is not directly necessary for tool selection or invocation.

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 zero-parameter, no-output-schema payment quote tool, the description is complete enough: it states what is returned, the price and payment rail, the exact HTTP call to make, and relevant data freshness caveats. An agent has enough information to call it and act on the result.

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?

The tool itself has zero input parameters, so the baseline is 4. The description goes further by documenting the downstream HTTP query parameters (cik required by example, period optional), which helps the agent understand what to send when paying the quote.

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 verb and resource: returns payment terms for a named SEC 13F endpoint. It also explicitly distinguishes itself from execution-oriented siblings by saying it 'never runs the check or pays,' so an agent can tell it apart from x402_check-style tools.

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?

It gives clear next-step instructions: pay the 402 over HTTP with x402 v2 and call GET ?cik=... with an optional period. It also states the tool itself does not run the check or pay, which defines its scope, though it does not explicitly name sibling alternatives such as x402_check or fetch.

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