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

No annotations are provided, so the description carries the full behavioral burden. It discloses the non-obvious secret lifecycle: setting the first webhook endpoint creates the signing secret, it is only returned when created or rotated, and the agent must record it at that time. It also states the authentication requirement. It does not describe other response contents, but the critical caveat is covered.

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 compact and well-organized into two functional paragraphs: scope plus the critical secret caveat, then access guidance. Every sentence contributes actionable information with no filler or repetition of schema content.

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 the complex nested schema and absence of an output schema, the description covers the most important contextual gaps: the authentication gate and the one-time-only secret return. It does not enumerate the full response shape, but for an update operation the provided caveats are the parts most likely to cause agent error.

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 description coverage is 100%, so the baseline is 3. The description adds meaningful cross-parameter behavior beyond the schema: the webhook secret creation/rotation and one-time return semantics, which is not inferable from the parameter definitions alone. It does not redundantly repeat the schema's field-level descriptions.

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 uses the specific verb 'Update' with a clear resource: account settings, and enumerates the exact scopes: branding, outbound webhook endpoint with event subscriptions, and default proof lifetime. This distinguishes it from related siblings like get_settings and start_login without needing to inspect 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?

The ACCESS note provides a concrete prerequisite (Proof account, authenticate via /mcp), instructs the agent to retry after authentication, and explicitly says start_login does NOT open this tool. It gives clear context but does not explicitly name sibling alternatives like get_settings or update_profile, so it stops short of full when-not guidance.

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