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

It discloses partial-update semantics ('Only the fields you pass are changed'), email and picture exclusions, the blank fallback for forum_display_name, and that an empty state clears the field. This adds behavioral detail beyond the annotations, though it does not describe exact response or failure behavior.

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-structured: a one-line summary, key exclusions, a bulleted Args list, and a Returns line. Every sentence adds signal and the most important usage constraints come first.

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 five-parameter mutation with no output schema and no per-parameter schema descriptions, the description provides all essential call guidance: field semantics, constraints, clearing behavior, and exclusions. No critical information is missing for an agent to invoke it correctly.

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?

With 0% schema description coverage, the description carries the full burden for parameter understanding. It documents each of the five parameters with max lengths, formats, and special behaviors (e.g., '' clears state, blank forum_display_name falls back to masked email).

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 opens with 'Update the authenticated user's profile fields,' a specific verb and resource, then enumerates the editable fields. It also marks email and profile-picture upload as out of scope, differentiating it from web-only profile actions and nearby update_* siblings.

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 explicitly states that email is not editable here and profile-picture upload is not exposed over MCP, giving clear boundary guidance. It does not explicitly name alternative tools such as update_user_preferences or get_user_profile, so some when-to-use routing is left to inference.

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