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

With no annotations, the description carries the burden. It discloses return values and that angle_c is in degrees, but doesn't mention error conditions (e.g., invalid triangles) or any side effects. It adds some transparency but lacks depth for edge cases.

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 short and front-loaded with 'Solve a triangle.' The mode explanations and output list are succinct. The final 'Runs on smart-tools.xyz' is a minor addition but not bloated.

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?

The tool has no output schema, but the description covers the output (sides, angles, area, perimeter) and the mode-specific inputs. It doesn't mention the locale parameter or error handling, but the schema covers locale. Overall, it is sufficient for a simple calculator.

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 coverage is 100%, so the baseline is 3. The description reiterates the mode-specific parameter relationships already captured in the schema, adding no new semantic detail beyond what's in the property descriptions.

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 clearly states the tool solves triangles, specifies two modes (sss and sas) with the required inputs, and lists the outputs (sides, angles, area, perimeter). This is a specific verb+resource, and it distinguishes itself from sibling calculators by focusing on triangle geometry.

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?

It explains the two usage modes with explicit input requirements, giving clear context for when to use each mode. It doesn't explicitly contrast with alternatives, but given the unique triangle scope among siblings, the usage is unambiguous and well-implied.

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