Regex tester

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

Discloses key behavior: without 'g' returns first match, with 'g' all matches. Also mentions return structure. No annotations provided, so description carries full burden and does it well.

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 succinct sentences, immediately clear, no redundant words. Front-loaded with the core purpose.

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?

Given the presence of an output schema (covers return values), the description adequately explains the tool's behavior and parameters. No gaps for a regex testing 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% (all 3 params described). Description adds value by explaining the effect of the 'g' flag on matching behavior, beyond the schema's brief 'Regex flags' description.

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?

Clearly states the action ('Run a JavaScript regular expression against a subject string') and the output ('return each match with its index, positional capture groups, and any named groups'). Sibling tools are unrelated, so no confusion.

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?

Describes the effect of the 'g' flag, guiding when to use it. No explicit comparison to alternatives, but siblings are orthogonal, so not needed.

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