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coinbase_attach

Attach to an open, signed-in Coinbase Advanced Trade tab in the debug profile. Returns attachment status, tab info, and probe results without falling back to unrelated tabs.

Instructions

Attach (fail-closed) to an already-open, already-signed-in Coinbase Advanced Trade tab in the debug profile. Returns { attached, signedIn, tab, probeResults }. Never falls back to an unrelated tab.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "coinbase_attach"
  }
}

Input Schema

Name	Required	Description	Default
`debugUrl`	No		http://127.0.0.1:9222
`urlContains`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.2.0Jul 12, 2026

TDQS

A4/5.0

Behavior4/5

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

With no annotations provided, the description takes on full responsibility for behavioral transparency. It discloses the return value shape and the 'fail-closed' behavior, indicating failure conditions. It does not contradict any implied behavior, and it adds useful context beyond the input schema.

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 extremely concise with only two sentences. It front-loads the core action and return format, and every word serves a purpose. There is no redundancy or unnecessary detail.

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

Completeness3/5

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

Given the tool has two parameters, no output schema, and no annotations, the description covers the basic purpose and return value but lacks explanation of parameter semantics and explicit failure scenarios. It is minimally adequate but leaves gaps for an agent to infer details.

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

Parameters2/5

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

Schema description coverage is 0%, so the description must compensate. However, it does not explain the purpose or usage of either 'debugUrl' or 'urlContains'. Default values are provided but without context, the agent cannot easily understand how to set these parameters correctly.

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 the tool's action ('attach'), the resource ('already-open, already-signed-in Coinbase Advanced Trade tab'), and the behavior ('fail-closed'). It distinguishes this tool from siblings by specifying the exclusive context of an existing tab, leaving no ambiguity.

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 provides clear context for when to use the tool (attaching to an existing tab) and implies not to use it for opening new tabs. The phrase 'Never falls back to an unrelated tab' sets a boundary, but it does not explicitly mention prerequisites or alternatives, which would strengthen it.

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