Set custom instructions for a style

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

Beyond the annotations (write, idempotent, non-destructive), the description discloses the critical behavior of overwriting existing instructions for the scope. It also clarifies merge semantics with global instructions and how get_style_guide returns the merged result, providing context not in the 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?

Every sentence is purposeful and informative. The description is front-loaded with the core purpose, followed by clear examples and scope behavior. No redundancy or fluff.

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 fully covers when to use it, overwriting behavior, global/specific scope, merging, and return behavior via get_style_guide. It is a complete guidance for an agent invoking this setter.

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% and both parameters already have descriptions. The description adds extra nuance about merge behavior and global vs. specific scope, which exceeds the schema but is not entirely new since the schema's styleId mentions global instructions. Thus a strong 4.

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's function: saving free-text drafting rules layered on top of a style's voice. It lists explicit examples of content types (required elements, audience notes, forbidden topics) and distinguishes scope (global vs. specific style), differentiating it from siblings like update_style and clear_style_instructions.

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 with user quotes ('always end with a CTA') and explains when to use global vs. style-scoped instructions. It also references get_style_guide for reading merged results, effectively guiding the agent to the correct alternative.

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