Start MITM proxy

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

With no annotations provided, the description carries the full burden and does so exceptionally well. It discloses that unmatched requests pass through, that scope only affects retained logs (not MITM behavior), and that the proxy still MITMs all hosts. This goes beyond a simple 'start' operation and sets accurate expectations, including a caveat about the Android emulator alias.

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 a single paragraph of four sentences, front-loading the core purpose in the first sentence. Each sentence earns its place: purpose/output, passthrough behavior, and a specific configuration hint. No redundant filler, perfectly sized for the tool's complexity.

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?

Given the tool's complexity (5 parameters, no output schema, no annotations), the description offers a complete picture: what it does, what it returns (LAN IP:port), how to use it with emulators, and how scope affects logging. It even warns about the proxy MITMing all hosts despite scope, covering edge cases. This is sufficient for an agent to invoke and interpret the result 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 already has 100% coverage with detailed per-parameter descriptions, so baseline is 3. The description adds extra value by explicitly explaining the practical use of hostRewrites (mapping 10.0.2.2 to 127.0.0.1) and clarifying that scope only controls log retention, not actual MITM behavior. This enriches the schema's information, justifying a 4.

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 the tool's primary action: 'Bring up the mockttp HTTPS MITM proxy.' It also specifies the output ('Returns the LAN IP : port') and distinguishes itself from siblings by being the start operation, unlike proxy_stop or proxy_list_traffic. The verb 'Bring up' is specific to the resource.

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 valuable contextual guidance, such as using hostRewrites for Android emulator devices and clarifying that unmatched requests pass through to the real headend. However, it does not explicitly contrast with alternatives like proxy_mock_response or proxy_scope, though the tool's role as the start command makes this implicit. The guidance is specific enough to be actionable.

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