Set the proxy mode

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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the description doesn't need to restate mutability. It adds valuable behavioral context beyond annotations: 'Existing connections may keep using the old proxy until they are reopened,' and it notes that the tool reads back what was written. It doesn't cover permissions or rate limits, but the added side-effect warning is meaningful.

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 front-loaded with the core action, then adds mode semantics, a side-effect warning, a pre-read recommendation, and a common example. Every sentence contributes useful guidance without fluff, though the example sentence could be considered optional; overall it 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?

Given 5 parameters, no output schema, and destructive annotations, the description covers the action, mode options, a key side effect, a restoration recommendation, and a common use case. It doesn't specify what the read-back response contains or whether a restart is needed, but for a proxy-setting tool with annotations covering the safety profile, it is largely 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?

Schema description coverage is 100%, and the schema already explains each parameter's role and mode association. The description's mode-value mapping ('mode: 0 none, 1 manual (give host/hostPort), 2 PAC (give pacUrl)...') largely repeats the schema, though the conditional 'give' phrasing adds marginal clarity. Per the baseline rule for high schema coverage, a 3 is appropriate.

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 states a specific verb and resource: 'Set the proxy configuration (network.proxy.* preferences) and read back what was written.' It explicitly distinguishes from the read counterpart browser_get_proxy, so an agent can identify which of the sibling tools to use.

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 instructs 'Read browser_get_proxy first so you can put the previous values back,' giving clear pre-use guidance, and it offers a common scenario (local HTTP proxy for testing). It doesn't state when not to use this tool or name any alternative besides the read counterpart, but the context is clear.

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