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

Annotations only declare the safety profile; the description adds genuinely new behavior: per-call cost of $0.01 (nothing on failure), dry_run defaulting to preview, and that leavers get suspended under suspend_leavers. It leaves one meaningful gap: what happens to directory users with no HR counterpart when suspend_leavers is off — created, ignored, or flagged.

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?

Four dense sentences in a logical order: what it does and how it matches, then each flag, then the default/safety behavior, then cost. No redundant restatement of the title or name, and nothing padding the text.

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 no-output-schema mutation tool with an empty param schema, the description covers effect, matching rule, safety default, and cost. What is still missing is the fate of unmatched directory users and any hint at what the dry-run plan looks like, which matters since there is no output schema to explain it.

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 0% — the schema carries only booleans and defaults with no descriptions. The description defines all three: dry_run shows the plan only, suspend_leavers also suspends HR-reported leavers, and include_managers pulls manager assignments. That fully compensates for the empty schema.

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 concrete verb pair (compare and set) plus both resources (HR's people and the directory) and the matching key (work email). That is enough to tell it apart from directory_update_user or admin_save_person, but it never names a sibling or explicitly contrasts itself with manual directory editing.

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 calling context (bring the directory in line with HR) and explains the effect of each flag, including that dry_run is the default and only previews. It stops short of naming alternatives or stating when not to use it, e.g. for a single-user correction.

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