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

With no annotations provided, the description carries the full burden. It discloses the key behavioral consequence (blocked identifiers cannot sign up or sign in), states the return value (created blocklist identifier summary), and includes cost. It does not mention reversibility or idempotency, but for a create operation this is reasonably transparent.

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 efficient and well-structured: it opens with the purpose, then gives the prerequisite, targeting logic, behavioral effect, return value, and cost. Every sentence adds necessary information with no redundancy or 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?

For a tool with 2 parameters (1 required) and a rich schema, the description covers the full workflow: how to select the instance, what the operation does, and what is returned. The existence of an output schema means return details do not need to be expanded. The cost note also adds practical context.

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 100%, so the schema already thoroughly documents both parameters. The description adds little beyond the prerequisite to call get_connected_accounts first, which is more usage guidance than parameter semantics. It does not enhance meaning of the parameters beyond what the schema provides.

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's action ('Add an identifier to the blocklist') and the specific resource ('blocklist identifier in a connected Clerk instance'). It distinguishes from sibling tools like create_allowlist_identifier by specifying the blocklist and the effect that blocked identifiers cannot sign up or sign in.

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 context: it explains the prerequisite to call clerk.get_connected_accounts first, and how to target a specific instance or default. It does not explicitly mention alternatives or exclusions, but the usage context is unambiguous. This is more than implied usage but lacks explicit alternative comparison.

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