Calculator

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

With no annotations provided, the description carries the burden of behavioral disclosure. It adds valuable safety context by stating 'Does not use eval' and 'Safely evaluate', but it doesn't disclose behavior for invalid expressions, division by zero, order of operations, or return type.

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 short sentences with zero filler. The action and scope are front-loaded, and the safety note is tucked in without bloat.

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 no output schema, the definition covers what the tool does, supported syntax, and a key safety property. It could mention the return value format (e.g., numeric result) or error handling, but the tool is simple enough that this is a minor gap.

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 schema alone says the parameter is a string containing an arithmetic expression. The description adds meaning by explicitly listing supported operators and parentheses, which helps the agent form a valid expression. Even with 100% schema coverage, this extra constraint detail elevates it above the baseline.

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') with a clear resource (basic arithmetic expression) and enumerates supported operators. This clearly distinguishes it from the unrelated sibling tools like text_stats, hash, or notes_list.

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 implies when to use the tool by saying 'basic arithmetic expression', but it never explicitly states when to prefer it over alternatives or when not to use it. For example, it doesn't say 'use this for simple math, not for complex calculations or scripting'.

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