Install an add-on from a file

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

Adds genuine behavior beyond the annotations: 'most add-ons work immediately; some need a restart' and the precondition that the path must exist and be readable by Firefox. The destructiveHint=true annotation is not explained (that installing grants the extension broad capabilities and that uninstall is the reversal path), which is the one material gap.

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 tight sentences, front-loaded with the action and accepted formats. The parenthetical AddonManager API reference earns its place only marginally but does not disrupt the flow.

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?

Covers input forms, preconditions, restart caveat, and the verification/enable/remove follow-up, which is sufficient for a one-parameter tool with no output schema. Missing are failure modes (unsigned/incompatible add-on errors, permission prompts), which an agent would still want.

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 single 'path' parameter already documents the .xpi/directory distinction and that it must be absolute. The description adds only the 'must exist and be readable' precondition, so the schema still carries most of the load.

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+resource ('Install an extension') and explicitly enumerates the two accepted input forms (.xpi file or unpacked directory), which distinguishes it from the userscript-oriented browser_tampermonkey_install sibling. An agent can tell immediately what this does 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?

Gives a concrete post-install workflow: verify with browser_list_addons, then branch to browser_set_addon_state or browser_uninstall_addon. That is real routing guidance. It stops short of saying when NOT to use it (e.g. signed-store installs or userscripts, which belong to browser_tampermonkey_install).

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