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

Adds behavioral details beyond annotations: binding type (plain_text), opt-in per site, effect on next function deploy. Consistent with idempotentHint=true. No contradictions.

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?

Three concise sentences with no fluff: core action, security context, and deployment timing. Every sentence adds value.

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?

Complete for a simple tool with two params and an output schema. Explains binding type, effect timing, and optional nature. Lacks explanation of 'Worker env' implications but output schema likely covers return values.

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 covers both parameters with descriptions (name, slug) at 100% coverage. Description reinforces 'saved variable' and 'owned site' but adds minimal new semantics beyond schema.

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 exposes a saved variable to one owned site's Worker environment as a plain_text binding. It specifies the resource (variable) and target (site), and distinguishes from siblings like delete_variable, set_variable, or attach_database.

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?

Provides clear context: use when you need a variable accessible to a site's Worker, and notes unattached variables are never injected. Does not explicitly name alternatives or exclusions, but gives enough guidance for correct use.

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