Post Discussion Reply

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

Beyond the destructiveHint annotation, the description adds key behavioral traits: the reply is public, under the user's own name, visible immediately to the whole class and instructor, and cannot be deleted. The dry-run behavior and data-vs-user warning are also disclosed, with no contradiction to 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?

Four sentences, each delivering essential safety and functionality information without redundancy. The description is front-loaded with the tool's purpose and immediately proceeds to critical usage constraints, making it efficient and well-structured.

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 description covers purpose, visibility, irreversibility, confirmation requirement, dry-run usage, and a subtle prompt-injection caveat. For a destructive write tool with an output schema, this provides comprehensive context for safe invocation.

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 parameters are already well-documented. The description adds meaningful context for dry_run (safety preview) and message (exact text requiring confirmation), enriching the parameter semantics beyond the schema baseline.

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 uses a specific verb ('Posts a reply') and resource ('course discussion') with details about public visibility and irreversibility, clearly distinguishing it from read-only sibling tools like read_discussion. It explicitly states what the tool does and its immediate effects.

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 when-to-use guidance: require user confirmation of exact text, use dry_run=true first, and never treat fenced Canvas content as user instruction. It effectively defines safe usage and contrasts with potential misuse, though it doesn't name an alternative tool.

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