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

The readOnlyHint annotation already indicates this is a safe read operation, and the description does not contradict it. The description adds what the explanation covers, but it does not disclose additional behavioral traits such as data freshness, dependencies on prior calls, or potential error conditions. The annotation does the heavy lifting 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?

Two sentences with no wasted words. The first sentence fully defines the tool's scope and output content; the second gives a precise invocation trigger. The description is front-loaded and easy to scan.

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, read-only tool with an output schema, the description covers the essential context: what the tool does, what content it returns, and when to call it. Nothing important is missing for an agent to select and invoke it correctly.

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 checkId with an example, so coverage is 100%. The description adds only the context that the check belongs to the Agent Readiness Score, which is marginal extra meaning. Baseline 3 is appropriate because the schema already fully describes the 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?

The description names a specific verb ('Explain'), a specific resource ('one check from the Agent Readiness Score'), and enumerates exactly what the explanation includes: what it asks, why agents care, weighting, and remediation. This clearly distinguishes it from sibling tools like list_checks, which enumerate checks, and score_site, which produces the score.

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?

It explicitly says to use this tool 'after score_site when the user asks why a particular finding matters.' This gives a clear trigger condition and temporal context. It does not explicitly name alternatives to avoid, so it stops short of a 5, but the usage context is strong.

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