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

With no annotations, the description carries the full burden. It discloses the return value ('Returns the created email address summary') and cost, and mentions a prerequisite call, but doesn't elaborate on side effects like verification emails or permissions. It provides some context but not rich behavioral disclosure.

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 concise and well-structured: purpose sentence, prerequisite/instance guidance, return summary, and cost. Each sentence earns its place with no unnecessary fluff.

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?

Given the 5-parameter schema with 100% coverage and the presence of an output schema (mentioned but not shown), the description covers the critical flow: what it does, the required first call, instance selection, and return value. It could mention side effects or permissions, but overall it's sufficiently complete for the complexity.

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 the baseline is 3. The description adds a bit of context for clerk_instance_id (call get_connected_accounts first), but this is partly redundant with the schema description which already says 'Omit to use the default connected account.' No significant additional meaning beyond 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 clearly states the tool creates an email address for a Clerk user with a specific verb and resource. While it doesn't explicitly differentiate from sibling tools like create_phone_number, the resource is unambiguous and the name reinforces the purpose.

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?

The description gives clear usage context by instructing to call clerk.get_connected_accounts first and explaining how to handle clerk_instance_id (target a specific connection or omit for default). It doesn't explicitly mention when not to use it or alternatives, so it stops short of a 5.

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