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

Annotations already declare readOnlyHint=false, destructiveHint=true, and openWorldHint=false, so the safety profile is covered. The description adds almost nothing beyond that surface: it never explains whether this is a partial or full update, what happens to flags not supplied (critical given zero required parameters), or what fb_user_label/connection_context are needed for.

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?

One tight sentence, front-loaded with the verb and target. No filler, though it is arguably too short to be useful given the schema gaps.

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 mutation with 5 parameters, 0 required, and 0% schema coverage, the description leaves key questions unanswered: how the target user is identified, whether omitted flags are preserved, and what connection_context must be. An output schema exists so return values need no explanation, but the input-side completeness is poor.

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 0% across 5 parameters, so the description carries the full burden. It names three of the five parameters (the allow_* flags) but adds no meaning beyond their names, and entirely omits fb_user_label (the target user) and connection_context (the required-looking routing token).

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 ('Update') and resource ('one FB user's ... flags') and names the three boolean permissions being changed. It does not differentiate from the nearby sibling fb_users_update_label, but the field-level specificity makes the intent unambiguous.

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?

There is no when-to-use, when-not-to-use, or alternative guidance at all, even though fb_users_update_label and fb_users_refresh_routing sit in the same family. The agent must infer that this is the tool for permission edits and nothing tells it how this differs from the label updater.

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