Compute the remainder of dividing one number by another and return an error when the divisor is zero.
Return the remainder of a divided by b. Returns an error if b is zero.
| Name | Required | Description | Default |
|---|---|---|---|
| a | Yes | ||
| b | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v1.0.4Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations exist, so the description carries the full behavioral burden. It usefully discloses the b=0 error condition, which is the key failure mode, but says nothing about negative operands, floating-point remainders, or result conventions (e.g., truncated vs. floored modulo).
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, the core operation front-loaded and the error edge case second. Zero wasted words.
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?
An output schema exists, so return-format explanation is unnecessary, and the definition covers the essential operation plus the one critical edge case. Only minor gaps (sign/float conventions) remain, which is acceptable for a simple arithmetic primitive.
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 0%, so the description must compensate. It assigns roles to both params (a = dividend, b = divisor) and adds the b≠0 constraint, which is meaning beyond the schema's bare 'A'/'B' titles, but it adds no format or range detail.
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 precise operation and resource: 'Return the remainder of a divided by b.' An agent can immediately distinguish this from math_divide, math_multiply, and the other arithmetic siblings without opening any schema.
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?
Usage is implied by the operation itself (compute a modulo when you need a remainder), but there is no explicit when-to-use guidance, no mention of the math_divide sibling it relates to, and no note on negative-number behavior. It is minimum-viable implied usage.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.