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

Annotations already establish readOnly, idempotent, non-destructive, closed-world behavior, so the bar is lower. The description adds genuine context beyond that: it discloses the two failure modes it reports (would compile from source needing a C/C++ toolchain and Python, or would fail) and that it returns an upgrade suggestion annotated with the upgrade's risk. It does not discuss latency or result size, but nothing is contradicted.

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 sentences, front-loaded with the scenario and followed by the result shape, with no filler. The second sentence is dense but each clause carries information (compile requirement, failure case, upgrade suggestion, risk).

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?

With three parameters, full schema coverage, and annotations already handling safety, the description covers what an agent needs: what it computes, when to run it, and rough shape of the answer. Since there is no output schema, it could have gone further in describing the returned recommendation format, but it is adequate for a read-only analysis tool.

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%, so all three parameters are documented in the input schema, and the baseline of 3 applies. The description adds little syntax or format detail beyond the schema; its only marginal contribution is implying that 'limit' controls how much of each upgrade's risk is surfaced, which the schema already states as 'max breaking changes shown'.

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 gives a concrete verb and resource: it checks which npm dependencies contain native code and whether a prebuilt binary exists for a target platform. That is specific enough to separate it from siblings like types_check or peer_check. It does not explicitly differentiate itself from upgrade_check, even though it also surfaces 'the nearest newer version' with upgrade risk, leaving some overlap for the agent to infer.

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 opening clause 'Before building on Alpine, Linux ARM, Windows ARM, a Mac or Lambda' gives a clear situational trigger for when to call this tool. There is no explicit when-not guidance and no sibling tool is named as an alternative, so the agent must infer the boundaries itself.

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