rec_start

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

Annotations only cover readOnly=false, destructive=false, and idempotent=true; the description adds substantial behavioral context beyond that. It discloses that recording runs in the background and stops on rec_stop, duration_s, max_events, or stop_when, explains cycle/change/poll mode semantics, describes pre-trigger buffering, and notes that events stream to a JSONL file.

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 dense paragraph that front-loads the purpose and then covers selection, modes, and triggers without obvious filler. It is information-rich and every sentence contributes, though the lack of formatting makes it slightly harder to scan than it could be.

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?

Given 12 parameters, multiple operating modes, trigger logic, and an output schema that handles return values, the description covers the core invocation details well. Minor gaps remain around name and max_symbols, and it does not compare this tool to related recording alternatives.

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?

With 0% schema description coverage, the description must carry the parameter burden, and it largely does: mode values and meanings, symbol selection via symbols/prefix/pattern with leaf-expansion semantics, cycle_ms behavior, start_when and stop_when examples, and pre_trigger_ms scope-style behavior. It leaves name and max_symbols unexplained, so it falls short of full coverage.

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 states a specific verb and resource: 'Start a continuous real-time recording of online PLC variables', and it names rec_stop as the lifecycle end. It does not, however, distinguish itself from siblings such as rec_profile_start or ads_watch, leaving some ambiguity about when this is the right start 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?

The description explains how to select symbols (explicit list, prefix expansion, fnmatch pattern), the three modes, and trigger syntax, which implies usage. It provides no explicit when-to-use or when-not-to-use guidance relative to alternatives like rec_profile_start, rec_scan, or ads_watch.

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