Draw a C4 level 1 (system context) diagram

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

No annotations are provided, so the description carries the burden of disclosing behavior. It does state that the tool returns a Mermaid diagram and describes what it includes. However, it does not mention side effects, failure modes, or whether an empty users/externalSystems list changes the output, though for a generation tool this is a moderate gap rather than a severe one.

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 concise and front-loaded: the first sentence states exactly what the tool does, followed by supporting context. The bilingual repetition is justified by the tool's language-aware nature and is not excessive. Overall, every sentence contributes functional or selection-relevant information.

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 diagram generation tool with no output schema, the description reasonably covers the output format (Mermaid), the diagram level (C4 context/level 1), and the supported element types. It could say more about defaults for empty arrays or how labels are generated, but the provided context is sufficient for correct invocation in most cases.

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 100%, so the schema already documents each parameter. The description adds conceptual meaning by explaining the intended diagram roles (people, system, external systems, short relationship labels), which maps to users, system, externalSystems, and relation, but it does not significantly extend the parameter-level semantics.

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 a specific verb (draw/return) and resource (C4 system context diagram, level 1, in Mermaid), and further specifies the diagram elements: people, system in scope, external systems, and relationship labels. This distinguishes it from the other diagram_* siblings like diagram_adm_cycle or diagram_value_stream because it names the C4 level 1 notation explicitly.

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 clear usage context: C4 is lightweight and suited when an executive must understand the system in thirty seconds. It does not explicitly name alternatives or state when not to use this tool, but the scenario guidance is strong enough for an agent to choose it appropriately among many diagram tools.

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