plc_update_ld

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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, so safety is covered. The description adds real value beyond that: staging (not committing) semantics, the automatic side effect of declaring new global dependencies as VAR_EXTERNAL, and the requirement to preserve unknown fields. It still omits what happens on a revision mismatch or how staging relates to plc_commit_changes.

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?

Two tight sentences, primary action front-loaded, with the precondition second. Domain jargon (VAR_EXTERNAL, rung objects) is dense but appropriate for the audience; nothing is wasted.

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 write tool inside a transaction workflow with four required parameters and thin schema coverage, the description should explain the transaction/section identifiers and how staging connects to commit. An output schema exists so return values needn't be described, but the parameter and transaction-lifecycle gaps remain.

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 only 25% — only expected_revision is documented in the schema. The description leaves transaction_id, section_id and the shape of the rungs array entirely unexplained; 'read original rungs first' hints that full objects are expected but adds no field-level meaning.

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 ('Stage') on a specific resource ('native Ladder rung objects') and names the secondary effect of registering VAR_EXTERNAL declarations. 'Native Ladder' implicitly contrasts with the sibling plc_update_st, though it never names it outright.

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?

It gives a procedural precondition ('Read original rungs first and preserve unknown fields'), which is genuinely useful. But it never states when to choose this over plc_update_st, nor when a transaction must be open or committed, so usage is only implied.

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