validate_dax

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

With no annotations provided, the description carries the full burden of disclosing behavior. It explicitly states the operation is non-mutating ('without changing anything') and reveals its implementation ('runs EVALUATE ROW'), which is valuable context. It does not detail error handling or return values, but the core safety behavior is clear.

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, front-loaded sentence that immediately states the action and includes all essential information: what it does, against what, and the safety guarantee. No wasted words.

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?

For a simple two-parameter tool with no output schema and no annotations, the description provides adequate context: purpose, safety, and implementation. It lacks explicit mention of return values or failure modes, but these are not critical for basic tool selection and 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?

The schema covers 50% of parameters (dax is described, sessionId is not). The description uses 'DAX expression' matching the schema, and 'live model' implies sessionId refers to a live model session, adding slight context. However, it does not fully compensate for the undocumented sessionId parameter.

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 validates a DAX expression against the live model, using a specific verb ('Validate') and resource ('DAX expression against the live model'). It distinguishes from siblings by noting 'without changing anything' and 'runs EVALUATE ROW', differentiating it from run_dax or dax_lint.

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 phrase 'without changing anything' provides clear context that this is a safe validation tool, implying it should be used when side effects are undesirable. However, it does not explicitly name alternatives like run_dax or dax_benchmark, so it falls short of a 5.

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