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

The description discloses the output structure: 'Returns area, perimeter, type (equilateral/isosceles/scalene).' It implies safe mathematical computation without side effects. No annotations are provided, so the description adequately covers behavioral traits.

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 consists of two short, front-loaded sentences. Each sentence serves a purpose: first defines the tool's function, second provides usage guidance and output summary. No 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?

Given the tool is a simple mathematical calculation with an output schema (context signals indicate present), the description sufficiently covers usage, parameters, and output. It lacks error conditions for invalid triangles, but overall complete for its complexity.

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 input schema covers 100% of parameters with descriptions and constraints. The description adds 'Inputs: sides a, b, c' but does not provide additional meaning beyond what the schema already specifies. Baseline 3 is appropriate.

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 explicitly states 'Compute triangle area from three side lengths using Heron's formula' and distinguishes from angle-based methods with 'Use when angles aren't known.' This clearly defines the action, resource, and differentiates from potential sibling tools.

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 provides explicit usage context: 'Use when angles aren't known.' It also references 'See list_bundles for related math calculators.' While it does not list alternatives or exclusions, the guidance is clear and practical.

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