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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the bar is lower, and the description still adds real behavioral content: what happens downstream when a wheel is missing, and that missing entries are accompanied by the nearest newer version with a wheel plus that upgrade's risk. It doesn't describe output shape, per-package error handling, or how partial/unparseable requirement lines are treated.

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 dense sentences with no filler, and the core answer (does a wheel exist) is front-loaded before the consequence. Minor cost: 'For each that's missing' has a loose antecedent and requires a re-read to bind to the packages just mentioned.

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 no output schema, the description does carry return-value burden, and it covers the main payloads: per-package wheel availability and, for misses, the nearest wheeled version plus upgrade risk. Given four well-documented parameters, the remaining gap — what a lockfile with unresolvable/loosely-pinned entries yields — is modest but not covered.

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 each parameter carries its own description with examples, so the schema does the heavy lifting. The description adds only indirect meaning — the 'nearest newer version with that upgrade's risk' behavior implicitly explains the `limit` parameter's role — without naming or elaborating any parameter.

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?

Names the specific resource (pinned Python packages) and the specific check (prebuilt wheel availability for a target Python version and platform), with concrete platform examples in parentheses. An agent can distinguish it from node_check/node_check-style siblings because the description is explicit about 'pip' and 'Python packages'. It never names a sibling directly, so it stops short of full 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 implied by the stated consequence ('without one, pip builds from source, which usually fails without a compiler'), which tells the agent the scenario this tool serves: pre-flight install planning on uncommon platforms. There is no explicit when-to-use vs. when-not, and no routing to native_check, upgrade_check, or package_info for adjacent questions.

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