design_system_set_default

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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the agent knows this is a mutating operation. The description adds valuable context: it affects only future document creation, not existing documents, and it can be cleared with null. This goes beyond what annotations provide and helps the agent understand the blast radius of the destructive action.

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?

Two sentences, zero waste. The core action is front-loaded, the null-clearing behavior is stated, and the key side-effect (existing documents retain their version) is included. Every word earns its place.

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 single-parameter mutation tool with no output schema, the description covers the essential context: what it does, what the parameter means, and the key behavioral caveat. It doesn't mention return values, but with no output schema that's less critical. The destructive annotation plus the description's scope limitation give the agent enough to call it correctly.

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 0%, so the description must compensate. The description explains that the 'system' parameter is the design-system version/digest to set, and that null clears it. This maps directly to the schema's anyOf [object, null] structure. However, it doesn't explain the individual fields (id, version, digest) beyond what the schema's patterns imply, but for a single-parameter tool this is adequate.

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 states a specific verb ('Set'), a specific resource ('design-system version/digest'), and the exact scope ('used by future document creation'). It also distinguishes itself from related operations by noting that existing documents retain their embedded version, which differentiates it from design_system_apply or design_system_save.

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 clearly states when to use this tool: to set the default design system for future document creation. It also explains the alternative behavior (existing documents are unaffected), which implies when not to use it (if you want to change existing documents, use design_system_apply instead). It doesn't explicitly name the alternative, but the context is clear enough.

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