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

With no annotations, the description carries the burden. It clearly indicates this is a read operation ('Retrieve') and states the return is a summary, but does not disclose behavior on invalid ids or missing records. The cost disclosure adds useful context.

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 in a logical order: purpose, prerequisite/usage, return value. 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?

The tool has an output schema, so return details are covered. The description covers the prerequisite, parameter usage, and return summary, but could additionally mention behavior for invalid IDs or instance mismatches. Still, it is adequate for a simple getter.

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 baseline is 3. The description adds value by explaining where clerk_instance_id comes from ('from clerk.get_connected_accounts') and that omitting it uses the default account, which enhances the schema's basic description.

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 opens with a clear verb+resource statement: 'Retrieve a Clerk email address by its id.' It distinguishes from siblings like get_phone_number or get_user by the specific resource, and mentions the return value ('email address summary').

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 explicitly instructs the agent to call clerk.get_connected_accounts first, providing a prerequisite. It also explains how to use clerk_instance_id to target a specific connection or omit it for default, but does not mention exclusions or alternatives.

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