⚠️ Block users

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

Beyond annotations (destructiveHint: true), the description adds important behavioral context: the user will be blocked from messaging, it affects a third party, and requires confirmation. This goes beyond the structured data.

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 relatively concise, with two main sentences and a brief enum listing. It is front-loaded with the purpose and warning, but the all-caps may be slightly noisy.

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 tool's complexity (4 parameters, no output schema), the description covers the essential purpose, warnings, and parameter summary. It omits details like error handling and return values, but is adequate for a destructive action.

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 schema already documents all parameters. The description summarizes the parameter structure and lists reason IDs, but this adds marginal value beyond the 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 action ('Adds one or more users to the account's BLACKLIST') and the resource (blacklist). The verb 'Adds' and resource are specific, and the tool is distinct from sibling messenger tools (e.g., sending messages, deleting messages).

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 provides clear context by warning about the irreversible effect and requirement for confirmation. However, it does not explicitly state when not to use this tool or name alternative tools for similar actions.

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