xpath_tool

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

With no annotations, the description carries the burden. It discloses the regex-based and lightweight nature, plus the limitation on complex axes, which is useful. However, it does not mention error behavior, return format, or whether the tool modifies input.

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 a single sentence, front-loaded with the core purpose, and every clause adds information about supported patterns or limitations. No redundancy or filler.

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 simple 3-parameter tool with no annotations or output schema, the description covers the main extraction functionality and constraints. However, it omits the behavior of the 'count' action and return value format, which are important for a complete invocation picture.

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 only 33%, with only the xpath parameter having examples. The description adds supported XPath forms for xpath, but says nothing about html or the action parameter (extract vs count), leaving those semantics incomplete.

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 it performs XPath extraction and enumerates supported patterns like //tag, tag, tag[@attr="value"], /text(). This specific verb+resource distinguishes it from sibling text/regex 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 notes this is a regex-based lightweight implementation and explicitly says it does not support complex axis expressions, giving a clear boundary for when to use it. It does not name specific alternatives but the limitation serves as implicit guidance.

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