Use persistent profile

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

The description discloses significant behavioral traits beyond annotations: 'Restarts the browser and closes every open page' and 'a second instance pointed at the same one fails to start.' These are critical side effects and failure modes not captured by the annotations' readOnly/destructive/idempotent hints. No contradiction with annotations.

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?

Four sentences, front-loaded with the core purpose, followed by usage motivation, side effects, prerequisites, and concurrency caveat. Every sentence carries essential information with no fluff.

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?

The description is complete for this tool: purpose, when to use, prerequisites, side effects, concurrency failure mode, and how to revert to ephemeral. Output schema exists so return values need no explanation. Sibling tools provide additional context.

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%, so the baseline is 3. The tool description repeats that the profile must already exist, but the schema already provides the full parameter meaning, including the ephemeral escape values. Thus the description adds no new semantic value beyond the structured schema.

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 'Switch the browser to a named persistent profile,' a specific verb and resource. It clearly distinguishes from siblings like create_profile, delete_profile, and use_temp_profile by focusing on using an existing profile.

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 explains when to use the tool ('pick up the cookies, logins and extensions stored in an earlier session'), gives a prerequisite ('create it first with create_profile'), and mentions the ephemeral alternative via special parameter values. It also warns about the single-instance constraint, which is practical usage guidance.

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