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

With no annotations, the description must carry the full behavioral disclosure, and it does usefully warn about ReDoS risk and a $0.002 cost. However, it does not explain side effects, matching semantics, what 'live matching' means operationally, or what happens on failure.

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?

A single compact sentence front-loads the main feature and includes the risk/cost caveat with no filler. The '...' shorthand and '$0.002' notation could be more precise, but the overall structure is efficient.

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 tool with six optional parameters and no schema descriptions, this description is thin: it fails to state what values kind accepts, what text is for, or how the template mode versus custom pattern mode is selected. The presence of an output schema reduces the need to describe return values, but invocation ambiguity remains significant.

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 0%, so the description must compensate, but it only hints at kind/pattern/samples. It leaves text, agent_id, and ignore_case unexplained, so an agent cannot reliably map the two described modes to the six available parameters.

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 defines two distinct operations: using a named regex template (email, url, eth_address, tx_hash) with live matching, and testing a custom pattern against samples. This is clear enough to differentiate the tool from its siblings, though it is phrased as a noun phrase rather than a direct 'builds/tests' verb.

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?

No guidance is provided about when to prefer this tool over sibling tools or which sibling alternatives exist. The only conditional is the tool's own internal 'or' between template-based matching and pattern testing, which does not help an agent choose this tool over alternatives.

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