Test Regular Expression

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

Annotations already declare readOnlyHint and idempotentHint, so the description adds value by specifying the exact output format (matches with index and capture groups). It also warns against reasoning about regex, a behavioral caveat beyond 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 description is three sentences, front-loaded with the core action, then usage guidance, then a supplementary link. Each sentence serves a purpose, with no redundancy or wasted words.

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 read-only utility tool with annotations covering safety, the description explains the action, output, and when to use it. It lacks explicit details on flags behavior and the maxMatches limit, but these are present in the schema. Overall, it is sufficient for an agent to call 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?

Schema description coverage is 75%, with pattern, text, and flags documented. The description does not add parameter-specific meaning beyond the schema; maxMatches is not described in the schema but has default and constraints, so the description does not need to compensate.

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 clearly states the tool executes a regex against text and returns every match with index and capture groups. It uses a specific verb and resource, and the mention of 'Use this instead of predicting' distinguishes it from reasoning or other regex-related utilities.

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 instructs to use this tool instead of predicting what a pattern matches, giving a clear when-to-use condition. While it doesn't name a specific alternative, it provides strong behavioral guidance and implies the tool is for actual execution rather than mental simulation.

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