Search Message Opens

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

Adds the important precondition that open tracking must be enabled, which is not covered by the readOnly/idempotent/openWorld annotations. This is a useful behavioral insight, though it does not detail what happens if tracking is disabled or how pagination behaves beyond schema descriptions.

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 a single, efficient sentence that front-loads the purpose and includes a key prerequisite in parentheses. No unnecessary words or repetition.

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 output schema and annotations cover return values and safety profile, while the description adds the open-tracking requirement. The main gap is the lack of parameter guidance for three filters, but overall the tool is simple enough that a capable agent can infer most usage.

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?

With only 40% of parameters described in the schema (count and offset), the description should compensate by explaining tag, recipient, and messagestream. It does not, leaving these filters ambiguous beyond their names.

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 searches email open events across outbound messages, using a specific verb and resource. It distinguishes itself from siblings like search_message_clicks by focusing on opens rather than clicks.

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 mentions a prerequisite (requires open tracking) but does not explicitly discuss when to use this tool versus similar alternatives like search_message_clicks or get_open_counts. Usage is implied by the tool's purpose rather than explicitly guided.

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