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

Annotations already flag destructiveHint=true, idempotentHint=false, and openWorldHint=true; the description goes beyond them by prescribing behavior the agent needs under those conditions — obtain explicit approval, never retry after an uncertain failure, check current state first. It does not say whether an omitted bio leaves the existing value intact or whether the picture is replaced wholesale, which is the one behavioral 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 short sentences, front-loaded with the scope constraint before the exclusion and the safety rules. Every clause carries information an agent needs; there is no restatement of the tool name or filler.

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 destructive, non-idempotent mutation with a nested object parameter and no output schema, the description supplies the essential operational guardrails (approval, no blind retry, inspect first) and the field scope. The remaining gap is partial-update semantics — what happens to bio or picture when only one is supplied — which matters for an idempotentHint=false tool.

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 only 33% — account_id and picture.content are documented in the schema, while bio, filename, and content_type are bare. The description confirms bio is text and picture is an image, and rules out other profile fields, which helps disambiguate the two top-level params, but it adds no format, size, or partial-update semantics to compensate for the undocumented nested fields.

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 states a specific verb and resource (update your own bio or profile picture) and immediately scopes it by naming what is unsupported (names and other profile fields). That exclusion cleanly separates it from facebook_update_post, facebook_update_comment, and the platform-twin instagram_update_my_profile / linkedin_update_my_profile tools.

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 says when this applies (only your own profile, only bio/picture) and gives operational conditions: require explicit user approval and inspect current state before acting. It stops short of naming the specific read tool (facebook_get_my_profile) as the way to inspect state, so the routing to a sibling is implied rather than explicit.

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