variance_analysis__material_price_variance

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

No behavioral details beyond the sign convention. The tool's formula, assumptions (e.g., whether it computes (act_price - std_price)*act_qty or similar), and any side effects are absent. No annotations are provided to compensate.

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?

The description is extremely short (one fragment), but it lacks a clear, front-loaded statement of purpose. It is under-specified rather than concise.

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?

Given no annotations, no output schema, and three undocumented parameters, the description is critically incomplete. An agent cannot safely invoke this tool without guessing the formula and parameter meanings.

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?

Parameters (std_price, act_price, act_qty) are not described in the schema or the description. The agent gets no explanation of what each parameter represents or expects, despite 0% schema description coverage.

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 only states a sign convention ('Positive = favorable.') but does not explicitly state that the tool computes material price variance. The tool's name provides some clue, but the description fails to clarify the purpose.

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?

No guidance on when to use this tool versus other variance analysis tools like labor_rate_variance or material_usage_variance. The description provides no context for selection.

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