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

With no annotations, the description carries the full burden and does so richly: signed Receipt v1.0, signature attests only what TunnelMind recorded (not truth), never calls the destination or carries your traffic/data, payment always goes to TunnelMind's x402 address, per-tier pricing charged in USDC, demo payments refused, and 503/404 semantics without charge.

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?

Front-loaded with the return payload, then behavioral/payment detail. It is long and somewhat dense, but nearly every sentence earns its place by disclosing behavior an agent needs; minor redundancy across the payment and error sentences.

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?

No output schema exists, yet the description fully characterizes the return: facts as {value, tier, source} with a coverage state, plus a signed Receipt v1.0. Combined with the payment/error semantics, an agent has everything needed to call and interpret results.

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 schema already documents both X-PAYMENT and capability. The description adds only marginal context ('capability slug from the referral catalog', X-PAYMENT absent on the first 402 call), so the baseline 3 holds.

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?

States a specific verb and resource: it returns a destination's endpoint and schema URL from a reviewed catalog plus observed facts (probe time, x402/Web Bot Auth, ASN/RPKI). The scope ('a capability TunnelMind does not provide itself') is clear, though it never explicitly contrasts with the similarly named sibling get_referral_log.

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?

Gives a clear when-to-use condition ('a capability TunnelMind does not provide itself') and documents outcomes that guide invocation: 402 challenge quotes price, 503 when paid tools are off, 404 for unknown capabilities with no charge. It does not name an alternative tool explicitly, so it stops short of the top band.

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