List the OAuth clients attached to the Mozilla account

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

Goes well past the readOnlyHint annotation: it discloses that no-session resolves to an empty array rather than throwing, that a session token is required internally, and that the mock account is expected to yield an empty list. These failure-mode and edge-case details are exactly what an agent needs before calling.

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?

Purpose is front-loaded in the first clause, followed by the measured edge-case notes. Slightly dense with internal jargon ("MEASURED:", "_fetchAttachedOAuthClients") but each sentence carries distinct information.

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 single-optional-parameter read tool with no output schema and minimal annotations, the description covers invocation, preconditions, and the empty-result case. The only gap is the shape of individual client/session entries, which the agent must discover empirically.

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?

The single parameter `refresh` is fully documented in the schema ("Bypass the 4-hour cache"), so baseline is 3. The description adds nothing about the cache behavior or when to force a refresh, leaving that meaning entirely to the 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?

States a specific verb and resource: "List devices and web sessions attached to the signed-in Mozilla account," and gives the underlying API name. The mention of browser_sync_probe distinguishes it from the neighboring sync tool without the agent opening either 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?

Clearly frames the condition under which the tool is meaningful (a real signed-in account) and warns that the browser_sync_probe mock account is a deliberate mismatch that returns empty. It doesn't explicitly say "use X instead if you need Y," but the when-not context is concrete.

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