browser_set_proxy

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

Without annotations, the description carries the full burden. It discloses that the proxy is set as a default and that existing sessions are unaffected. However, it does not mention required permissions, error handling, or what happens on invalid input. For a simple configuration tool, this is adequate but not exhaustive.

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 two sentences, front-loading the core purpose in the first sentence and adding a crucial behavioral note in the second. No redundant or unnecessary wording. Every sentence earns its place.

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 3 parameters (1 required) and an output schema, the description is minimal. It covers the main purpose and a key constraint but lacks parameter guidance and output details. Since an output schema exists, return value explanation is less critical, but the description still feels incomplete for a tool with several parameters.

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 0% (no parameter descriptions in schema). The description does not elaborate on any parameters, even though 'server' is required and 'username'/'password' are optional. The parameter names are self-explanatory, but the description should have provided context (e.g., 'set the proxy server address'). It adds no value beyond the schema's bare names.

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 purpose: 'Pin a proxy as the default for subsequent sessions/identities.' It uses a specific verb ('pin') and resource ('proxy'), and the unique capability sets it apart from sibling tools, none of which manage proxy configuration.

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 provides context: 'Proxies are bound at launch, so existing sessions are unaffected.' This tells the agent when to use the tool (for new sessions/identities) and implicitly warns against using it to affect current sessions. No alternatives are mentioned, but the guidance is clear.

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