get_inspected_element

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

The description discloses a key behavioral trait: the tool depends on a prior marking step, not just a read of a live selection. This goes beyond the readOnlyHint annotation by explaining the stateful prerequisite. It does not mention the failure mode if no element is marked, but the output schema likely covers the return shape.

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 sentences: the first states the purpose, the second gives the prerequisite procedure. No filler or repetition, and the critical info is front-loaded.

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 getter with no parameters and an output schema, the description covers the essential 'how' and 'when.' The only minor gap is not stating the behavior when no element has been marked, but this is a low-complexity tool and the description is otherwise complete.

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?

The tool has zero parameters, so the baseline is 4. The description provides no parameter-specific semantics because there are none, and no schema coverage is needed.

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's function: 'Get the element marked for MCP inspection.' The verb 'Get' plus the specific resource 'inspected element' distinguishes it from sibling getters like get_html or get_computed_style. The additional instruction on how to mark an element removes ambiguity.

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 provides explicit steps to prepare the element for inspection ('select it in the Elements panel, then run window.$0 = $0'), which is practical usage guidance. While it doesn't explicitly state 'use this when you need the inspected element reference,' the context implies it, and no alternatives are mentioned.

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