fail

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

Despite having no annotations, the description fully discloses the behavioral profile: it raises a ToolError, produces a clean is_error result, carries a message, and avoids an unexpected server crash. This gives the agent accurate expectations without needing annotations.

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 short and front-loaded: the first sentence states the core action and purpose, and the second adds necessary technical behavior. Every sentence earns its place with no redundancy.

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 zero-parameter demonstration tool, the description is complete. It explains why the tool exists, what behavior to expect, and how errors will appear. The output schema supplies return-value details, so nothing essential is missing.

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?

There are no parameters, so per the rubric the baseline is 4. The description mentions that the error carries a message, but since the schema defines no parameters, there is nothing further to document.

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 specific purpose: 'Intentionally fail to demonstrate how tool errors reach the client.' It uses a specific verb ('fail') and immediately explains the intended use, distinguishing it from the functional sibling tools like add, multiply, and echo.

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 a clear context for use: to demonstrate how tool errors reach the client. While it does not explicitly name alternatives or when-not-to-use scenarios, the sibling tools are clearly functional operations, and this tool's demonstration purpose is unambiguous.

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