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 one genuinely useful behavioral fact: a per-call cost of $0.0005 USDC, which matters for agent budgeting. It says nothing about the evaluation engine, precision/rounding, input restrictions (e.g., whether arbitrary code or variables are accepted), or error behavior on malformed expressions.

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?

Three short sentences with zero filler; the core action is front-loaded and the cost note is a compact trailing fact. Every sentence earns its place.

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 one-parameter tool with full schema coverage and no output schema, the description covers purpose, scope, and cost adequately. The main remaining gap is the return shape (numeric string vs. formatted answer, units handling), which is not conveyed by any structured field.

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% and the single parameter already carries three illustrative expression formats, so the schema does the semantic work. The description adds only the general capability categories, not syntax, variable, or precision semantics beyond what the schema shows.

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 verb ('Evaluate') and resource ('mathematical expressions'), then enumerates concrete capability domains (arithmetic, algebra, unit conversions, trigonometry, matrices). No sibling in the provided list performs math evaluation, and the description makes that separation obvious without needing schema inspection.

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 capability list implies when the tool applies, but there is no explicit when-to-use/when-not-to-use framing and no named alternative. Usage is inferable rather than stated, which is the definition of minimum-viable guidance for a tool with no real competitors.

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