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

Annotations cover the safety profile (idempotent, non-destructive, non-read-only), and the description adds the details annotations cannot express: the human is notified, permission roles required, and the resolved-state precondition. That is exactly the calibration example's 'credit for adding context' standard.

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, each with a distinct payload: the action, the unassign escape hatch, then the preconditions. Front-loaded with no 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 two-parameter mutation with no output schema, the description covers the side effect, permissions, and the failure precondition, which is what an agent needs to call it safely. It omits only what the response or failure looks like, a minor gap given the annotation coverage.

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 itemId's source (list_items) and assignee's accepted forms (name/email/id/'me'/null) are already documented. The description's 'pass null to unassign' duplicates the schema; only the notification consequence tied to assignee adds marginal meaning. Baseline 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?

States a specific verb and resource ('hand an item to a person') plus the defining consequence (the assignee is notified). No sibling tool in the list performs assignment, so this is unambiguously distinguishable from set_status, create_item, or post_update.

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?

Gives clear operating conditions: null assignee to unassign, only owners/admins/collaborators may assign, and resolved items must be reopened first. It stops short of naming an alternative tool or an explicit 'do not use when' case, but the preconditions are strong enough that an agent knows when the call will fail.

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