echo_error

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

With no annotations, the description carries the full burden, and it does disclose the single most important behavioral fact: the tool never returns normally but always raises a ToolError. It does not detail the error payload or invocation cost, but the critical trait is stated plainly.

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?

A single short sentence that is front-loaded with the essential behavior. Every word 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?

An output schema exists, but since the tool always raises, return values are moot and need no explanation. The description is complete for this simple one-param error tool, only lacking a note on when it would be used.

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 0%, so the description must compensate. Saying the error is raised 'with the given message' clarifies that the sole parameter becomes the error text, which is meaningful added value, though it doesn't cover format or type constraints.

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?

States a specific and unusual behavior ('Always raises a ToolError') with the resource being the given message. This clearly distinguishes it from the echo family and other utility siblings, which return values rather than raising errors. It stops short of naming a sibling alternative, so a 5 isn't warranted.

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?

No guidance on when to use this tool versus the many echo/string siblings, nor any stated purpose such as testing error handling. The agent must infer its intent from the behavior alone.

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