case_open

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

Annotations indicate a non-read-only, non-idempotent, non-destructive operation, and the description adds meaningful behavioral detail: it writes only under $OPS_HOME, never touches a VMware system, and never overwrites an existing case. It also reveals that the return value contains a ceiling grade and advises reading it immediately, which is valuable runtime guidance.

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 compact and well-structured with labeled sections: [WRITE], WHEN, RETURNS, and GOTCHAS. Every section earns its place, and the most important decision guidance is front-loaded.

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 when to use the tool, return shape, a critical return-value caveat, and key behavioral constraints. Since there is no output schema, a bit more detail on fields like path, state, grade, and next would have made it fully self-contained, but the provided guidance is sufficient for an agent to call the tool 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 coverage is 100%, with rich parameter descriptions already covering summary, determined_by, window_start, and product_versions. The tool description itself does not add parameter-level detail, so the baseline score of 3 is appropriate; the schema already does the heavy lifting.

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 opens with '[WRITE] Open an investigation case — step 01, define the event,' naming a specific action and resource. It clearly establishes this as the starting point for a reasoned investigation, which distinguishes it from lookup and read tools like incident_timeline and case_get.

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 WHEN section explicitly states the intended situation: 'at the start of an incident you expect to reason about rather than glance at.' It also names the alternative for a different context: 'For a one-off lookup use incident_timeline alone.' This gives the agent an explicit routing rule.

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