Go Back

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

Beyond the annotations, the description reveals important behavioral nuance: it 'goes through the page' rather than issuing a browser-level command, and it verifies the result against the tab URL instead of assuming success. This adds meaningful context that annotations alone do not provide. No contradiction with readOnlyHint=false or destructiveHint=false.

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, no filler, with the core action front-loaded and the second sentence dedicated to a high-value differentiator. Every phrase contributes to correct invocation or selection.

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 an optional-parameter navigation tool, the description plus schema and annotations cover the main operational requirements well. The main gap is the absence of any explicit statement about return value or output shape, but this is a minor omission given the simplicity of the operation and the absence of an output schema.

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 100%, and the input schema already documents tab_id, timeout_ms, and wait_until_loaded in detail. The tool description itself adds no parameter-level meaning, so the baseline of 3 applies.

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 opens with a specific verb and resource: 'Navigate a tab back in history.' It immediately distinguishes the tool from forward navigation and from Arc's native command by noting it works on background tabs. An agent can understand exactly what this tool does without opening the schema.

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?

The description gives a clear use case: navigating a background tab back, which it explicitly contrasts with 'Arc's own back command.' It does not explicitly enumerate when not to use this tool or compare it to sibling tools like go_forward, so it stops short of full when/when-not guidance.

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