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

With no annotations, the description carries the behavioral burden; it discloses the access requirement, the need to authenticate before retrying, and that start_login will not lead into this tool. It stops short of stating whether updates are partial or how the mutation affects the public profile, but the core write behavior and prerequisite are explicit.

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 core purpose is front-loaded in the first sentence, the supported fields are a compact list, and the access note is separated visually. No filler or redundant restatement of the parameter names exists.

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 tool with 8 optional parameters and nested objects, the definition supplies the missing non-schema context: authentication, account requirement, and the fact that the target is the caller's primary profile. It does not explain the difference from update_profile in depth, but the schema covers optionality and the main invocation path is clear.

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 schema already documents every parameter. The description's field list groups parameters into semantic categories (e.g., 'verification display settings' for show_proof_channels and show_verification_dates), which is marginal added value, so the baseline of 3 is appropriate.

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 names a precise operation—'Update the current user's primary profile'—and enumerates exactly which fields it touches (display name, bio, avatar, theme, custom links, verification display settings). The 'current user's primary profile' qualifier distinguishes it from the generic sibling update_profile and from read-only get_my_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?

It gives a clear precondition (Proof account), a required auth step, and an explicit when-not: 'start_login does NOT open this tool.' It does not name the alternative tool for updating non-primary profiles, so the guidance is strong but not fully exhaustive.

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