ads_call_method

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

Annotations already flag readOnlyHint=false and destructiveHint=true; the description is consistent ('Write-class') and adds substance the annotations cannot: the TcRpcEnable prerequisite and the ordering/type constraints for arguments. It still does not describe failure modes on the PLC side or whether a partial write can occur.

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?

Terse and front-loaded: the purpose comes first, then the prerequisite, then the argument contract. The telegraphic fragments ('Write-class.', parenthetical type note) are dense but each carries information; no filler sentences.

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?

An output schema exists, so return values need not be explained, and the description covers the essential calling contract plus the RPC-enable prerequisite. Missing pieces are secondary: how to address the FB instance, error behavior, and side effects of a destructive write-class call.

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. It does well on two of the five parameters (exact shapes for inputs as {type,value} and outputs as type-name strings, with VAR_INPUT/VAR_OUTPUT ordering and a base-type warning), but says nothing about instance, method, or return_type, which are the required/optional identifiers.

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: invoking an FB method on a running PLC over ADS RPC, which is distinct from the symbol-level ads_read/ads_write siblings. It does not explicitly name a sibling it competes with, so an agent must infer that this is the only method-invocation tool.

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 real precondition (the method must carry {attribute 'TcRpcEnable'}) and labels the operation 'Write-class', which steers the agent toward mutating-use context. It stops short of stating when to prefer this over ads_write/ads_write_many or what to do if the attribute is absent.

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