Enable or disable an add-on

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

Annotations declare a non-read-only, destructive-hinted mutation; the description adds genuinely new behavioral facts: it requires a privileged context (AddonManager) and that disabling is reversible, which softens the destructive hint and tells the agent the state change can be undone. The privilege requirement is the kind of failure-mode context annotations cannot express. It does not cover error behavior if the privileged path is unavailable, keeping it below a 5.

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?

Three short sentences, action front-loaded before the rationale and the id source; nothing is filler. The 'MEASURED:' marker is slightly idiosyncratic but signals verified context and does not obstruct reading.

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 two-parameter toggle with full schema coverage, no output schema, and annotations already carrying the safety profile, the description supplies the remaining essentials: the privilege requirement, the id source, and reversibility. Nothing an agent needs in order to call it correctly is missing.

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%, with both parameters documented including the enable/disable boolean semantics. The description's pointer to browser_list_addons for ids largely restates what the schema already says, so it adds little beyond the baseline.

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 (turn on/off) and a specific resource (installed extension by id), which distinguishes it cleanly from the sibling tools browser_install_addon and browser_uninstall_addon. An agent can identify the operation 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?

It gives the prerequisite path explicitly ('get ids from browser_list_addons') and explains why this route is used (BiDi lacks webExtension.* commands), which is real selection context. It stops short of naming when to prefer browser_install_addon / browser_uninstall_addon instead, so it is clear context without explicit alternatives.

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