x402 Doctor

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only describes the tool's function and does not mention whether it is read-only, requires authentication, has side effects, or any performance considerations. The implied read-only nature is not stated explicitly.

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 two sentences: the first explains what the tool does, the second provides usage guidance. It is front-loaded, compact, and contains no unnecessary words.

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?

For a simple one-parameter tool with no output schema, the description covers the purpose and a use-case. However, it lacks parameter format details and does not describe the return structure beyond 'Full explanation'. Given the absence of an output schema, more detail on the response would improve completeness.

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 description coverage is 0%, so the description must compensate. It adds 'by id' indicating the parameter is an identifier for a rule, but does not explain the format, source, or how to obtain valid IDs. This is minimal added meaning beyond the bare schema.

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 provides a 'Full explanation of one rule by id' and enumerates the content (what it checks, why it matters, how to fix it, where the rule came from). This is a specific verb+resource combination. However, it does not explicitly differentiate from sibling tools like 'list_checks', though the intent is clear enough for an agent.

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?

The description includes 'Use when you want the reasoning without re-probing,' which gives a clear use-case but no explicit when-not-to-use or alternatives. Siblings are not mentioned, so the guidance is implied rather than explicit.

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

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions the tool returns the whole rule table, but does not disclose behavior like whether it requires authentication, what happens if called with no rules, the format of the output, or any side effects (e.g., destructive actions). The description is too brief for a tool with zero annotation coverage.

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 extremely concise at one sentence. It is front-loaded with the core purpose and adds a meaningful second thought. Every word serves a purpose, though it could potentially be slightly more structured (e.g., a clear 'Returns: ...' statement), but it remains efficient and clear for its brevity.

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 has no parameters and no output schema, the description should complete the picture by explaining what the output contains (e.g., list of rule names, statuses? ). It hints at the value but does not specify the output format or structure. For a zero-param tool, a slightly richer description of the output would make it fully self-contained.

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 has zero parameters and schema description coverage is 100%, so there are no parameters to document. The description adds value by explaining the conceptual meaning of the ‘whole rule table’ and why it matters (knowing what wasn't checked), which goes beyond what the empty schema conveys. A baseline of 4 is appropriate given no parameters and good schema coverage.

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 'The whole rule table' conveys the tool returns a complete listing of rules, and the additional context about 'what was NOT checked' adds nuance about the purpose. It clearly distinguishes from siblings like 'explain_defect' (which explains defects) and 'probe_x402_endpoint' (which probes a specific endpoint), making the tool's role as a rule-listing tool clear.

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?

The phrase 'Knowing what was NOT checked is part of knowing what a clean result means' implies this tool should be used to understand the full scope of checks performed, especially when interpreting a clean result. However, there is no explicit guidance on when to use it versus the siblings, nor when not to use it. The usage context is implied rather than explicit.

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

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

No annotations are provided, so the description carries full burden. It thoroughly explains the tool's behavior: performs a GET without X-PAYMENT header, checks the 402 challenge against 16 rules, and returns specific status categories (healthy, advisories, defects_found, not_x402, unreachable). It also clarifies that each finding cites its source (spec or facilitator rejection). This is comprehensive and goes beyond the minimal.

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 fairly concise for the amount of information it conveys. It front-loads the core action and then details the handshake process, rule checking, and status reporting. It could be slightly shorter by removing some redundancy (e.g., 'what it observes about it' is unnecessary), but it is well-structured and efficient given the 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?

The description is complete for a tool with one parameter, no output schema, and no nested objects. It explains the input constraints, the probing logic (including the handshake and rule checks), and the possible return statuses. No missing information is apparent given the tool's complexity. The lack of an output schema is compensated by the detailed description of the output categories.

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?

There is only one parameter (url) with 100% schema description coverage. The description adds context by noting that private and loopback addresses are refused, which is not in the schema description. This adds practical usage guidance beyond the schema. The high schema coverage means the baseline is 3, and the extra context justifies 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 what the tool does: it probes an x402 seller endpoint and reports observations. It distinguishes itself from sibling tools like 'explain_defect' and 'list_checks' by focusing on endpoint probing rather than defect explanation or check listing. The verb 'probe' and resource 'x402 seller endpoint' are specific and unambiguous.

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?

The description implies when to use this tool: to test an x402 endpoint and get a health status. It does not explicitly state when not to use it or mention alternatives, but the context of sibling tools ('explain_defect', 'list_checks') provides some differentiation. The lack of exclusions is a minor gap, but the use case is sufficiently clear.

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