x402 Package Advisories

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

With no annotations, the description carries the behavioral burden, and it delivers by disclosing the return contents (status, version, tool prices, network, x402 endpoints) and the cost ('Free'). It omits any statement about side effects or auth, but for an inherently read-only diagnostic that is a minor gap.

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?

Two tight sentences with the core purpose ('Free health check') front-loaded and the returned fields listed immediately after. No filler or redundant restatement of the name.

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?

There is no output schema, so the description must convey the return surface, and it does so by naming the key returned fields. The enumeration is somewhat terse ('network', 'the plain-HTTP x402 endpoints') and doesn't detail response shape, but it is adequate for a parameterless health endpoint.

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 takes zero parameters, so the schema has nothing to document. The baseline for a 0-parameter tool is 4, and nothing in the description misrepresents or requires parameter explanation.

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 function ('Free health check') and enumerates what it returns (service status, version, tool prices, network, x402 endpoints), so the agent knows exactly what this endpoint provides. It does not differentiate itself from the sibling 'ping', which could plausibly serve a similar connectivity-verification role, so it lands at 4 rather than 5.

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?

'Free health check' implies a diagnostic use case and the 'Free' flag hints at a no-cost call, giving implied usage guidance. However, it offers no explicit when-to-use condition, no exclusions, and no mention of how it relates to the sibling 'ping' as an alternative.

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 burden and largely meets it: it discloses pricing ($0.01 USDC per call via x402), that bad input and upstream errors are not charged, and data provenance/licensing (OSV.dev CC-BY 4.0, deps.dev). It omits auth/wallet setup details implied by x402 and any rate-limit behavior.

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 core action and scope, then layers input formats and return shape efficiently with zero filler. The middle sentences are densely packed into run-ons, which slightly hurts scanability but every clause carries 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?

No output schema exists, and the description fully compensates by enumerating the return payload (per-package vulnerable flag, vuln count, max severity, max CVSS v3, recommended upgrade, advisory fields, severity totals, unique vulns, skipped entries). An agent has enough to decide, invoke, 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 already 100%, so the schema documents each parameter, but the description adds real meaning: the three alternative input shapes, worked example strings for the comma format, and the semantic rule that range minimums are used for package.json versions.

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 ('Audit up to 50 dependencies in one call') plus the backing service (OSV.dev querybatch). The batch scope of up to 50 packages implicitly distinguishes it from the single-package siblings package_advisories and vuln_details.

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 concrete entry paths (items array, packages string, manifest text, or raw POST body) and names the manifest formats accepted, so an agent knows how to invoke it. It stops short of saying when to prefer this over package_advisories or vuln_details for a single package or a deep advisory dive.

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 burden and does so: it discloses deduplication of GHSA vs PYSEC/GO records, that the recommended upgrade is re-checked against OSV, the data sources and their licensing (OSV.dev CC-BY 4.0, deps.dev), the charging model ($0.003 USDC via x402) and that failed/unknown lookups are not charged. That covers cost, side effects and failure modes that structured fields do not.

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 purpose is front-loaded in the first sentence and the remainder is grouped logically by return payload, provenance and pricing. The long enumeration of returned fields is dense but justified since there is no output schema; a few items (the trailing '...' ecosystem list, duplicated ecosystem names) are mild 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 tool with no output schema and no annotations, the description supplies the return shape in detail, the deduplication rule, the advisory sources, error/charging behavior and the payment requirement. Nothing an agent needs to call it correctly or interpret the result is missing.

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 all four parameters are already documented, and the description's 'omit version' note merely restates the schema default. It adds no new meaning for ecosystem aliasing or include_withdrawn, so the baseline 3 applies.

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 first clause names a specific verb and resource — 'Security advisories for one open-source package version' — and the parenthetical ecosystem list pins the exact domain. The 'one package version' scoping implicitly separates it from manifest_audit (whole manifest) and vuln_details (single advisory), so an agent can pick it without opening other schemas.

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?

There is explicit guidance for one parameter ('Omit version to check the latest stable release'), which tells the agent how to do a latest-release sweep. However, it never says when to prefer this over manifest_audit or vuln_details, nor any precondition such as needing to know the ecosystem string first. Usage is implied by the scope statement rather than stated.

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 burden and does well: it discloses that the call is paid, the exact cost ($0.001 USDC), the payment mechanism (x402), and the return payload (ok plus timestamp). It stops short of describing failure modes, e.g. what the agent sees if payment is rejected.

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 zero filler; purpose comes first, usage and cost follow. Every sentence carries information an agent needs before calling a paid endpoint.

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 zero-parameter tool with no output schema or annotations, the description supplies the essentials: purpose, return values, and the payment precondition. Minor gaps (timestamp format, error behavior on failed payment) are acceptable at this complexity level.

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 takes zero parameters, so the baseline of 4 applies. There is nothing for the description to clarify beyond what the empty schema already conveys, and it adds no misleading parameter language.

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: a paid connectivity test that returns 'ok' and a server timestamp, which is more than a tautology. It does not, however, distinguish itself from the sibling 'health' tool, which an agent will almost certainly consider alongside it.

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 triggering context: use it to verify the x402 payment flow end to end. It omits any when-not-to-use guidance, notably that a free alternative (health) exists for plain liveness checks, so the agent must infer that distinction.

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 supplied, the description carries the behavioral burden and does it well: it discloses the $0.001 USDC x402 charge, states that unknown ids and upstream errors are not charged, and names the upstream sources and license. It does not describe response shape beyond enumerating fields, but the pricing and error-billing behavior are the operationally important details here.

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 core capability is front-loaded in the first clause, with return contents listed immediately after and cost placed last. The field enumeration is long but each item (aliases, affected ranges, severity, CVSS) tells the agent something about whether the response will answer its question.

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-id lookup with no output schema, the description adequately previews the return payload — aliases, affected packages and ranges, references, credits, database_specific, normalized severity and computed CVSS. The remaining gap is that the pitfalls of the narrow id pattern and any rate limits or truncation behavior are not mentioned.

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 there is only one parameter, whose description already says 'OSV id or CVE alias'. The description adds the concrete accepted id prefixes, which is genuine extra meaning about what forms are valid, but the pattern constraint and required-ness are fully handled by the 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?

States a specific resource — the full OSV record for a single vulnerability id — and enumerates the accepted id namespaces (GHSA, CVE, PYSEC, GO, RUSTSEC, OSV), so it is clearly a per-id lookup rather than the package-level sibling calls. It never explicitly names package_advisories as the alternative, so it stops short of full sibling differentiation.

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 is only implied: it is clear you call this once you have a vulnerability id, and the note that unknown ids are not charged encourages trying uncertain ids. There is no statement of when to prefer this over package_advisories or manifest_audit, which are the natural entry points for the same data.

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