k402

pay_per_call

Complete a PER-CALL coin payment. After a paid tool returns a 402 with pay_per_call_offers, pay one offer on-chain from your own wallet, then call this with the 402's endpoint and request_body, the chosen offer's scheme and payment_id, and your payment txid. The gateway verifies the payment landed and returns the tool's real result. (Alternative to a prepaid session — use this when you'd rather pay each call directly in a specific coin.)

Input Schema

TableJSON Schema

Name	Required	Description	Default
`txid`	Yes
`scheme`	Yes
`endpoint`	Yes
`payment_id`	Yes
`request_body`	Yes

TDQS

A4.6/5.0

Behavior4/5

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

No annotations provided, so the description carries full burden. It describes the complete workflow: pay on-chain, call with details, gateway verifies and returns result. Lacks details on failure modes but is generally transparent.

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

Conciseness4/5

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

Description is concise with three sentences, front-loading the purpose and then the parameters. Could be slightly more structured but minimal waste.

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

Completeness4/5

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

Covers the essential steps for a complex payment flow. Mentions the return value ('real result'). Could include more on error handling, but adequate for an agent to understand usage.

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

Parameters5/5

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

Schema coverage is 0%, so description must compensate. It explicitly links each parameter to its source: endpoint and request_body from the 402, scheme and payment_id from the chosen offer, and txid from the payment. Adds critical meaning beyond schema names.

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 uses a specific verb 'complete' and resource 'per-call coin payment'. It explains the context (after a 402 with pay_per_call_offers) and lists the required parameters, distinguishing it from a prepaid session.

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

Usage Guidelines5/5

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

Explicitly states when to use: after a paid tool returns 402 with pay_per_call_offers. Also mentions the alternative prepaid session, providing clear guidance on choosing this tool over its sibling.

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

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TDQS

A3.7/5.0

Disambiguation5/5

Each tool has a clearly distinct purpose, with detailed descriptions that prevent ambiguity. Even within related domains (e.g., covenant operations, proving steps), the functions are well-separated and described.

Naming Consistency4/5

Most tools follow a verb_noun or noun_noun pattern with underscores, but there are some single-verb names like 'catalog' and 'classify'. Within subdomains naming is consistent (e.g., kaspa_*, covenant_*, prove_*). Minor deviations prevent a perfect score.

Tool Count3/5

36 tools is on the high side for a typical MCP server, but the broad scope (blockchain, payments, ZK proving, text processing, search, registry) justifies the count. It borders on being too large for easy navigation but remains reasonable.

Completeness4/5

The server covers a wide range of functionalities with no critical gaps for its stated domain. Minor gaps exist (e.g., no direct Kaspa send transaction tool), but the covenant tools provide a workaround. Overall, the surface is fairly complete.

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