Turn Global Privacy Control on or off

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

Beyond the annotations (readOnlyHint=false, destructiveHint=true), the description discloses the actual behavioral effect on outgoing requests and the environment prerequisite. It stops short of saying whether the setting persists across sessions or is per-profile only, which matters for a state-changing privacy toggle.

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?

Front-loaded with the effect, then the parameter caveat, then the runtime prerequisite — a sensible order with no filler. The parameter-shape warning is slightly redundant against a schema that already names the key `gpc`, costing a bit of tightness.

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 one-boolean-parameter tool with annotations and no output schema, the definition covers purpose, effect, and prerequisite adequately. Only the persistence/scope question and sibling routing are unaddressed.

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% and the schema already documents `gpc` as 'true to send Sec-GPC, false to stop sending it'. The 'MEASURED' note reinforces the exact key name and the error text, which helps recovery from a malformed call, but adds little semantic meaning beyond the schema itself — baseline 3.

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?

States a specific verb pair (enable/disable) and a concrete resource (the Global Privacy Control signal), plus the observable effect of the request header Sec-GPC: 1. It is clearly distinguishable from the sibling browser_get_gpc, which reads rather than sets the signal.

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 hard prerequisite (Marionette-only, Firefox must run with --marionette), which is genuinely useful usage guidance. However, it never says when to reach for this versus browser_get_gpc or the broader tracking-protection/pref tools, so the choice between siblings is left to inference.

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