Call an endpoint (x402-aware)

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

Annotations indicate readOnlyHint=false, destructiveHint=false, etc., but the description adds valuable behavioral details: the server cannot pay (no private key), 402 responses yield a payment challenge, and paymentHeader is forwarded untouched as X-PAYMENT. This goes beyond the schema and annotations, informing the agent of important limitations.

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?

Two sentences, front-loaded with the primary action, then concise conditions and payment guidance. No filler or redundancy. Every sentence earns its place.

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 generic endpoint caller with 5 params, nested objects, and no output schema, the description covers the essential behavioral context: success returns the response, 402 returns a payment challenge, and the server's inability to pay. This is sufficient given the tool's open-ended nature.

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 coverage is 100%, so the baseline is 3. The description adds semantic value by explaining that paymentHeader is forwarded as X-PAYMENT and clarifying the 402 flow, which is not fully captured in the schema's parameter descriptions. This enriches understanding of how the paymentHeader parameter functions.

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 clearly states 'Call an endpoint and return its response' with a specific verb and resource. It distinguishes this from sibling tools (agent search, reputation, jobs, settlements) by focusing on generic endpoint invocation with x402 payment handling.

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 provides clear context for use: call any endpoint, with special handling for 402 payment challenges. While it doesn't explicitly mention alternatives or when-not-to-use, the purpose is self-evident given sibling tools are domain-specific. The payment guidance adds practical usage direction.

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