ads_write

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

Annotations already declare destructiveHint=true and readOnlyHint=false, but the description adds meaningful context: 'Returns before/after' and the gating rule ('readonly=never; guarded=write_allowlist; full=denylist only') tell the agent how writes are permitted in each mode. It stops short of warning about irreversibility or confirming a write actually took effect.

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?

Three dense sentences, front-loaded with the core action, then the value formats, then the gating rule. No wasted words, though the accepted-literal list could be more tightly framed.

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 needn't be spelled out, yet the description still notes 'Returns before/after'. For a destructive single-write tool with 0% param coverage, it covers value formats and permission gating adequately but leaves the name parameter and cross-tool routing unaddressed.

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 must carry the load. It does explain the value parameter's accepted forms (scalars, lists, literals like 'T#1s500ms', 'D#2026-10-15', '16#FF'), which is genuinely additive, but the required 'name' parameter (the symbol identifier) is never explained.

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 ('Write a symbol on the running PLC') with the target context ('running'). It is clearly a single-symbol write, which implicitly separates it from ads_write_many and ads_write_raw, but it never names those siblings so the agent must infer the distinction.

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?

There is no explicit when-to-use/when-not guidance and no routing to alternatives such as ads_write_many for multiple symbols or ads_read to check current values. The 'Gated' clause describes permission modes rather than selection context, so usage must be inferred.

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