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

With no annotations provided, the description carries the full burden. It discloses key behavioral traits: statelessness ('no job is created, no database row written'), the $0.01 USDC cost per attempt, the two-call protocol with expected responses, and the relationship to paid product tools. This is comprehensive and exceeds what annotations would typically provide.

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 relatively long but each sentence contributes meaningful information: the flow, cost, statelessness, and use case. While it could be tightened, the structure logically moves from purpose to flow to benefits, making it effective despite its length.

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 description is complete for the tool's complexity: it covers the two-call flow, expected response format, cost, side effects (none), and when to use it. No output schema exists, but the description describes the response structure ('{paid: true, timestamp, receipt_ref, payment_method}') so the agent knows what to expect.

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 schema already has 100% coverage for the single parameter, so the baseline is 3. The description adds value by explaining the credential's role in the two-call flow, providing an example format ('Payment eyJ...'), and explicitly stating to omit it on the first call. This enriches the schema's description without redundancy.

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 this is a smoke test for MPP payment plumbing, with a specific verb ('smoke-test') and resource ('MPP payment plumbing via this MCP server'). It distinguishes itself from sibling paid tools by explicitly noting it uses the same verification path as transcribe/summarize but costs only $0.01 USDC and creates no job.

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?

Explicit usage guidance is provided: 'Use this whenever you want to confirm a wallet, the MCP transport, the worker, and the production payment middleware are all healthy without paying a transcribe price.' It also explains the two-call flow, making it clear when and how to use it as an alternative to paid tools.

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