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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds substantial non-schema behavior: exact pricing tiers with min/max, the 402 quote-before-pay flow, no account/API key, invalid input refused before payment, and failed runs never charged. That is precisely the kind of payment and failure semantics an agent cannot infer from the annotations.

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 and scope are front-loaded well, but the pricing is stated twice in near-identical form ('0.002 USDC per unique package version (minimum 0.01, maximum 0.2), quoted exactly in the 402' then 'Price: 0.002 USDC per advisory_check (0.01-0.2 per call...)'), and the full percent-encoded URL is bulky. Roughly a third of the text could be cut without information loss.

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 carries the burden of describing returns, which it does by naming per-package status, advisory ids with summary, severity and fixed versions. Payment and pre-payment validation are covered; what remains thin is error handling beyond invalid input and any rate-limit or batch-size failure behavior.

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 schema already gives both input formats with examples, so the baseline is 3. The description earns above baseline by adding the 2-100 cardinality constraint and the 'mixed ecosystems' semantics, plus a concrete encoded URL that shows how the list is serialized.

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 ('OSV advisory check of 2-100 package versions in one call, mixed ecosystems') and enumerates the returned fields (status, advisory ids, severity, fixed versions). It distinguishes itself from single-package siblings only implicitly via the batch range; it never names deps_check_advisories or deps_audit_project as the non-batch alternatives.

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 by '2-100 package versions in one call' and by the 'How to call it: get_example' pointer, plus the HTTP URL equivalent. There is no explicit statement of when to prefer this over deps_check_advisories (single) or deps_audit_project (whole manifest), which are the obvious competing choices.

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