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

With no annotations, the description must fully disclose behavioral traits. It only states 'Expression discarded,' which is cryptic and fails to explain what the tool does with any of the schema parameters, what side effects occur, or what output to expect. The safety and action profile of the tool is completely opaque.

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 extremely short (single sentence) but under-specifies the tool's function. It is not appropriately sized; it sacrifices necessary information for brevity and leaves the agent confused about the tool's capabilities given the mismatched schema.

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 9 parameters, no output schema, and no annotations. The description does nothing to explain how parameters are used, what the tool returns, or how it integrates with sibling validators/hints. It is completely inadequate for an agent to correctly call this tool.

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 each parameter is already described in the schema. The tool description adds no meaning to parameters; it doesn't even reference them. Baseline of 3 is appropriate because the schema handles parameter documentation, but the description fails to tie parameters to the tool's purpose.

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 claims to evaluate 'a+b style arithmetic' but the schema has 9 unrelated string parameters (ref, url, city, feed, host, json, path, zone, query) that have nothing to do with arithmetic. This is misleading and does not align with the tool's actual function. It does not distinguish from siblings and provides a false purpose.

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?

There is no guidance on when to use this tool versus alternatives. The description only mentions expression evaluation with no context about appropriate scenarios, exclusions, or relationships to sibling tools.

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