tia_apply_hmi_project

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

Goes well past the annotations: it discloses the compile/save/reopen verification sequence, that partial failed output is retained rather than rolled back, that two headless TIA sessions are consumed, and a concrete timeout envelope (TIA_MCP_HMI_WRITE_TIMEOUT_MS, default 15 min). These are exactly the operational traits an agent needs before committing to a multi-minute mutation.

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?

Front-loaded with the action and its approval gate, then side effects, then cost. Every clause is informative, though 'Two headless TIA sessions' is telegraphic and would land harder if it stated the consequence (session slot contention).

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 non-idempotent mutation with no output schema, the description covers the safety gate, durability of partial results, verification, and runtime cost. The remaining gap is the confirmToken acquisition path, which an agent must know in order to supply all three required parameters.

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 0%, so the description carries the burden. 'Explicit approval of the exact immutable plan' conveys the intent of the approval and planSha256 parameters (approval binds to a specific plan hash), but the confirmToken parameter is never explained — where it comes from or its lifetime is left entirely to the schema's uuid format.

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?

States a specific verb and resource ('Create a new isolated classic WinCC project') and immediately bounds the scope with what it is not ('Does not attach to an existing project or download'). The word 'classic' distinguishes it from the sibling tia_apply_unified_hmi_project without the agent having to open either schema.

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?

Gives a hard precondition — 'only after explicit approval of the exact immutable plan' — which routes the agent to the plan-creation step first, and excludes two adjacent behaviors (attach, download). It does not name the specific sibling plan tool to call beforehand, so the routing is implied rather than explicit.

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