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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds 'Deterministic text,' which is a useful behavioral trait beyond the annotations, indicating the output is stable and predictable. No contradiction with annotations.

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 two sentences, front-loaded with the primary function and immediate informative detail about the three primitives. Every sentence earns its place; no redundant or filler content.

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 simple no-parameter explanation tool, the description fully specifies what it returns (write-up of three named primitives), when to use it (user asks about modeling primitives), and that it is deterministic. Annotations cover safety, and no output schema is needed for a text-returning tool. It is complete for its purpose.

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 tool has zero parameters, so the input schema is empty and there is no parameter semantics to explain. Baseline for 0 params is 4, and the description correctly focuses on the tool's content and usage rather than inventing parameter details.

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 returns a focused write-up of the three DRS modeling primitives, explicitly naming Constraint, Buffer, and Interrupt. This specific verb+resource distinguishes it from sibling explanation tools like explain_des_vs_drs_event_complexity or explain_discrete_rate_simulation.

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 gives an explicit usage condition: 'Use this when the user asks specifically about modeling primitives or how to spell a system in DRS.' This effectively tells the agent when to select this tool and implicitly when to consider alternatives among the explanation-focused siblings.

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