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

With no annotations, the description carries the full behavioral burden and largely succeeds: it discloses network probing and the key side effect of 'auto-adds confirmed services to the local directory.' It does not mention rate limits, idempotency, or behavior toward already-known services, so it is not a 5.

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?

Three sentences, each earning its place: the target and purpose, the execution steps, and the return output. There is no filler, repetition, or irrelevant detail.

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 tool with no output schema and no annotations, the return contract is only described as a 'summary of newly discovered services' — enough to know the general kind of result but not its shape or contents. The tool's effect on existing directory entries and behavior at max_results is also left implicit.

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 single parameter max_results is already fully described in the input schema with a default of 20, and the description adds no extra semantics about how the limit affects crawling or discovery. This aligns with the baseline for high schema_description_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 identifies a concrete action, target, and outcome: 'Crawl x402scan.com resources page to discover new x402 endpoints.' It also details the process (extract URLs, probe for support, auto-add confirmed services) and returns a summary, which clearly differentiates it from the sibling discovery/search tools.

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 intended use is clear: run it to discover and auto-add new x402 endpoints found on the resources page. It does not explicitly state when not to use it or name alternatives, but the context is unambiguous enough for an agent to select it over the other discovery/search tools.

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 the burden of explaining behavior. It does convey what information is returned ('paths, methods, prices, and well-known discovery files'), which is useful. However, it does not explicitly state that the operation is read-only, whether it performs network requests, or what happens on failure, leaving some behavioral ambiguity.

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, front-loaded sentence that immediately states the tool's purpose and quickly lists the main output categories. Every phrase contributes meaning, and there is no wasted or redundant wording.

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 tool with one well-documented parameter and no output schema, the description gives a reasonable overview of what the tool returns. It is likely enough for an agent to decide whether to call it and what to expect, though it stops short of detailing exact response structure or edge cases.

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 documents the single 'name' parameter with 100% coverage, including guidance that it should come from x402_search results. The description adds minimal semantic value beyond the schema, so the baseline of 3 is appropriate; there is no parameter documentation gap but also no extra clarification.

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 retrieves detailed information about a specific x402 endpoint and enumerates the key content: paths, methods, prices, and well-known discovery files. It is specific about the verb and resource, though it doesn't explicitly differentiate itself from sibling tools like x402_discover_urls or x402_fetch.

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 provides no explicit guidance on when to use this tool versus alternatives such as x402_search, x402_discover_urls, or x402_fetch. The input schema's mention of 'Service name from x402_search results' implies a workflow, but the description itself does not state when this tool is appropriate or when another sibling should be used.

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 behavioral burden and adequately discloses that the tool performs network fetches to three specific well-known paths and returns a unified discovery object. It does not detail error behavior, authentication, or failure cases, but the network-read nature is clear.

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 tight sentences with no filler. It leads with the core action, lists the fetched endpoints, and summarizes the returned object, every sentence earning its place.

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 one-parameter tool with no output schema, the description conveys the essential return fields (chains, wallet, endpoints, prices) and the discovery mechanism. It does not specify the exact output shape or failure behavior, but the tool is simple enough that this is a minor gap.

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% and the single url parameter is already documented with a description and example. The tool description adds no additional parameter semantics beyond restating that the URL is the service base URL, so baseline 3 is appropriate.

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 names a specific verb and resource: discover an x402 service by URL, and enumerates the exact well-known endpoints fetched. It is clear on its own but does not explicitly distinguish itself from the sibling x402_discover_urls, which may cover the plural/multi-URL case.

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 usage: use this when you have a base URL and need discovery details such as chains, wallet, endpoints, and prices. It does not explicitly state when not to use it or mention alternative sibling tools, notably the similarly named x402_discover_urls.

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, and it delivers: it reveals the probing targets (/.well-known/x402 and ai-catalog.json), discloses that requests run in parallel (which has rate-limit and load implications the agent should know), and states the return shape is a summary array. Minor gaps remain — no disclosure of failure handling, malformed-URL behavior, or what the summary entries contain — but the core operational traits are honestly surfaced.

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?

Three sentences totaling roughly 40 words, perfectly front-loaded with the core purpose. Each sentence earns its place: batch/parallel scope, probing targets, and return shape. There is zero filler, no repetition of schema content, and no buried critical information — the most important operational fact (parallel batch discovery) leads.

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 single-parameter tool with 100% schema coverage and no output schema, the description covers the essentials: what the tool does, how it operates (which endpoints it probes), and what it returns. The main omission is the contents of the 'summary array' — an agent doesn't know what fields or statuses to expect in the results — and there's no explicit pointer to the singular sibling. Both are minor given the low complexity, but they keep this from a 5.

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%: the urls parameter has a description and concrete examples ('https://svm402.com', 'https://2s.io'). The description adds mild value by explaining what happens to each URL (it is probed for the two discovery files), which enriches the parameter's meaning slightly. No additional format, normalization, or constraint details are needed given the schema already handles it — baseline 3 is appropriate.

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 opens with a specific verb-resource-scope pairing: 'Batch discover multiple x402 services in parallel.' It goes further, specifying exactly what probing occurs (/.well-known/x402 and ai-catalog.json), which makes the tool's behavior concrete. The word 'Batch' and 'multiple... in parallel' clearly differentiate it from the singular sibling x402_discover_url without needing to open either schema.

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?

Usage context is implied through 'Batch... multiple... in parallel' — an agent can infer this is for multi-URL discovery rather than single-URL discovery via x402_discover_url. However, the description never names the sibling alternative or states an explicit when-to-use/when-not-to-use rule. The distinction is inferable but left to the agent to deduce, so it stops short of explicit guidance.

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, the description carries the full behavioral burden. It discloses significant non-obvious behavior: automatic 402 payment handling, support for Base/Solana/Casper, and that wallets/payment details are hidden from the agent. It does not mention payment costs, failure behavior, or response format, but it covers the most important hidden traits.

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?

Three short sentences with no fluff. The core action, automatic payment behavior, supported chains, and privacy property are front-loaded. Every sentence conveys useful operational information.

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 payment-related complexity and lack of annotations/output schema, the description conveys the core behavior well. The main gap is that it does not describe what is returned (raw response, status, parsed body) nor explicitly caution that invoking it may incur payment, so an agent has to infer some operational expectations.

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 description coverage is 100%, so the baseline is 3. The description adds only 'optional body' as extra context, which lightly reinforces the schema but does not deepen understanding of method/chain/body semantics beyond what the parameter descriptions already provide.

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 states a specific verb ('Fetch') and a specific resource ('any x402-paid endpoint'), and clarifies that payment challenge handling is automatic. This clearly differentiates it from sibling discovery/health/description tools like x402_search and x402_describe, which do not actually fetch paid endpoints.

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 'Fetch any x402-paid endpoint' and 'Just provide a URL and optional body' establishes the core use case: call this tool when you have a concrete x402 URL to invoke. It does not explicitly name sibling alternatives or state when not to use it, but the context makes the primary usage clear.

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, the description carries the behavioral disclosure burden. It clearly indicates that the tool probes a service over the network, expects a 402 response, and does not itself make a payment. It does not describe the exact return format or error behavior, but the core side-effect profile is transparent.

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 with no filler. The first sentence states the mechanism and expected response; the second explains why it matters. Each sentence earns its place and the most important information is front-loaded.

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 health-check tool with no output schema and no annotations, the description covers what is checked, how it is checked, and when to use it. It does not spell out the return value, but 'Check if' strongly implies a boolean or status result, so the omission is minor.

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%, with both 'url' and 'name' already clearly documented as alternatives. The description does not add detail beyond what the schema provides, so the baseline of 3 is appropriate.

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 states a specific action ('Check if an x402 service is live and responding with 402 Payment Required') and a clear resource ('x402 service'). It also connects the check to a concrete use case ('before an agent pays for it'), which distinguishes it from sibling tools like x402_search or x402_fetch.

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 gives a clear usage context: use this tool to verify a service is operational before paying. It does not explicitly name alternatives or say when not to use the tool, but the purpose is distinct enough from the siblings that an agent can infer the right situation.

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 behavioral disclosure burden. 'List' appropriately signals a read-only action with no side effects, and 'all available' plus 'with counts' adds scope and output expectations. It does not mention authentication, rate limits, or exact response formatting, but for a zero-parameter listing tool this is a reasonable level of transparency.

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, front-loaded sentence that contains no filler. Every phrase earns its place: the resource, the scope, and the expected output detail are all present without redundancy.

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 zero-parameter list tool, the description is largely complete: it names the resource, states the scope ('all available'), and indicates the output includes counts. It falls slightly short by not defining the exact return shape and by leaving 'counts' slightly ambiguous, but this is a minor gap given the tool's low complexity.

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 tool has no parameters and the input schema is empty, so there is nothing for the description to clarify about parameter semantics. Given the zero-parameter baseline, the description adequately avoids inventing meaningless parameter details.

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 uses a specific verb ('List') and a concrete resource ('all available x402 endpoint categories'), with a clear output detail ('with counts'). This clearly distinguishes it from siblings like x402_search, x402_fetch, and x402_health, which serve different purposes.

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 its usage: it is the tool to call when an agent needs a category-level overview of x402 endpoints. However, it does not explicitly state when to prefer this over sibling tools or mention any exclusions or alternative routing, so the guidance remains implicit 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 present, so the description must convey behavioral context itself. It discloses the read-only search nature and the contents of results, but omits details like pagination, match semantics, filtering behavior (AND/OR), or potential rate limits. The behavioral disclosure is adequate but 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 two sentences, front-loads the action, and wastes no words. It efficiently conveys both the search capability and the return payload without redundancy.

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?

Without an output schema, the description compensates by listing what results contain. It covers the essential invocation knowledge: resource, filters, and return shape. Minor gaps exist around how filters combine and whether results are paginated, but for a simple search tool this is nearly complete.

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 documents all three parameters with 100% coverage. The description restates the filter axes (keyword, category, chain) at a high level, which adds a little context about their role, but does not add new meaning beyond the schema. This aligns with the baseline of 3.

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 opens with the verb 'Search' and names the specific resource 'x402 endpoints' for keyword, category, or chain. It also states the return payload (descriptions, prices, URLs), making the tool's function unambiguous and distinct from siblings like x402_list_categories.

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 clearly implies the tool is for finding x402 endpoints via filters, but it does not explicitly state when to prefer this over alternatives like x402_list_categories or x402_discover_urls. An agent can infer usage context, but no exclusions or when-not-to-use guidance is provided.

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