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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explicitly states the tool is 'documentation only (read-only / idempotent)' and 'does not charge or place trades,' which is important safety context for an agent considering whether to invoke it. It does not discuss rate limits or data freshness, but for a read-only instruction tool, the disclosed behavior is sufficient.

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 concise and well-structured: purpose first, then when-to-use, then side-effect disclaimer, then parameter values, then pairing with a sibling. Every sentence contributes new information with no repetition or 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?

The tool is simple (one optional parameter) and an output schema exists, so the description does not need to explain return values. It covers the parameter's allowed values, the tool's read-only behavior, what content will be returned, and the related sibling to use next. Nothing essential is missing for an agent to invoke it 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?

The input schema has no descriptions and 0% coverage, but the description compensates by defining the only parameter: '`product` is `signals` or `edgar-m-and-a`.' This gives the agent the allowed values and implied selection semantics beyond the bare schema title and default. It doesn't explicitly state the parameter is optional, but the schema already provides the default.

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 uses a specific verb and resource: 'Return subscription / paid-unlock instructions for PredMaker x402 products.' It clearly differentiates the tool from its siblings by naming the exact output and explicitly pairing with get_x402_payment_challenge, so an agent can determine what this tool uniquely provides.

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 says 'Call when you need the canonical price, treasury, freemium quota, and HTTP steps to unlock full payloads,' giving an explicit trigger condition. It also states what the tool does not do ('Does not charge or place trades') and names the sibling to pair with for a live challenge body, effectively routing the agent to the correct alternative.

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