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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds essentially nothing beyond that: it doesn't say whether evaluation is symbolic or numeric, what happens at non-existent limits, or how infinite limits are handled — and the direction claim merely repeats the schema enum.

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 tight sentences with the core operation front-loaded and no filler. It is efficient, though it leaves little room for the guidance an agent may want.

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?

With a fully documented 4-parameter schema and an output schema present, the description needn't explain return values or parameter formats. For a single-purpose calculator, the definition is adequate, falling short only on when-to-use routing.

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%, including the enum for direction and defaults for variable, so the baseline of 3 applies. The description's only parameter-adjacent content (left/right/two-sided) restates the schema rather than adding syntax or edge-case meaning.

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+resource ('Limit of an expression as a variable approaches a point'), which cleanly separates it from calculus siblings like derivative and integral. It doesn't explicitly name those siblings, but the operation is unambiguous.

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 says nothing about when to use this versus calculator_derivative, calculator_numerical_solve, or other calculus tools, nor any prerequisite or limitation. The 'supports left/right/two-sided' clause is a capability statement, not selection guidance.

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