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

Annotations only declare readOnlyHint and openWorldHint. The description adds meaningful behavioral context beyond that: it flags catastrophic backtracking, missing anchors, unescaped dots, [A-z] ranges, alternation precedence mistakes, and instructs the agent to check hasBlockingIssue first. No contradiction with 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?

Core purpose and critical warning are front-loaded. The 'WHY DELEGATE THIS' and ownership lines add useful context but go slightly beyond the minimum needed for invocation, so it is not perfectly concise.

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 tool with no output schema, the description provides enough guidance: input format, when to use it, and a hint about the result ('Check hasBlockingIssue first'). It does not fully specify the return shape, which is a minor gap.

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 the parameter is already documented as a JavaScript regex, bare or as /pattern/flags. The description reinforces this with examples but does not add meaningful parameter semantics beyond 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?

The description states a specific verb ('explain') and resource ('regular expression') and adds a second distinct capability ('detect catastrophic backtracking'). It is clearly distinguishable from the unrelated sibling tools.

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 gives an explicit trigger: 'ALWAYS call this before putting a pattern where it will run against untrusted input', with a concrete ReDoS example. It does not give an explicit when-not-to-use or name an alternative tool, but the condition is precise and actionable.

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