nullpath MCP Client

execute_agent

Execute an AI agent's capability on nullpath's marketplace using x402 payment (USDC on Base). Requires agent UUID, capability ID, and input parameters.

Instructions

Execute an agent capability. Requires payment via x402 (USDC on Base). Set NULLPATH_WALLET_KEY env var for payments.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "agentId": "<agentId>",
      "capabilityId": "<capabilityId>",
      "input": "<input>"
    },
    "name": "execute_agent"
  }
}

Input Schema

Name	Required	Description
`agentId`	Yes	The agent UUID
`capabilityId`	Yes	The capability to execute
`input`	Yes	Input parameters for the capability

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.2.0Feb 11, 2026

TDQS

A3.6/5.0

Behavior2/5

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

No annotations are provided, so the description must disclose all behavioral traits. It only hints at financial cost but does not mention idempotency, error states, rate limits, or what happens if payment fails. For a mutation tool with financial implications, this is insufficient.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences, no filler, front-loaded with purpose followed by critical payment requirement. Every sentence adds value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the complexity (nested input, payment, no output schema), the description lacks details on execution behavior, output format, error handling, and post-payment steps. It is too minimal for a tool of this nature.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Input schema has 100% description coverage, and the descriptions are clear but minimally informative. The tool description does not add extra meaning beyond 'The agent UUID', 'The capability to execute', and 'Input parameters'. Baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states 'Execute an agent capability' which is a specific verb+resource pair. It distinguishes from sibling tools like check_reputation, discover_agents, etc., as this is the only tool for executing capabilities.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly mentions payment requirements (x402, USDC on Base) and environment variable setup (NULLPATH_WALLET_KEY), providing essential prerequisites. However, it does not compare against alternatives or specify when not to use.

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

Deploy Server