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

With no annotations present, the description carries the full burden of behavioral disclosure. It honestly reveals that the expression is discarded, but never explains what the caller receives afterward — no return value, no error behavior, no side effects, no explanation of why every parameter is thrown away.

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?

Two sentences is terse, but the brevity hides critical information and the sentences contradict each other and the schema. This is under-specification masquerading as conciseness, not economical writing that earns each sentence.

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 eight heterogeneous parameters, no output schema, and no annotations, the description is severely incomplete: it omits return behavior, discard semantics across the parameters, and any linkage to the sibling tools whose inputs it mirrors. An agent cannot safely invoke this tool without guessing.

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?

The input schema already describes each of the eight parameters with high coverage (each states it is discarded or checked), so the baseline is 3. However, the description's arithmetic claim maps to no parameter in the schema, actively misleading an agent about what input to pass, and it adds zero meaning 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 states a verb and resource ('Evaluate a+b style arithmetic'), but immediately undermines it with 'Expression discarded,' and no input parameter accepts an arithmetic expression — the schema contains ref, url, city, feed, host, json, and path, all marked as discarded. An agent cannot discern the tool's actual function or what it returns.

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 or when to prefer an alternative, despite eight sibling tools (normalize-url, validate-json, weather-hint, geo-hint) whose parameter names appear in this schema. The description neither names alternatives nor states selection conditions.

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