fl_set_loop_mode

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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the agent knows this is a mutating operation. The description adds value by explaining that FL's native API is toggle-only and this tool wraps it to provide an absolute set, which is a meaningful behavioral disclosure. The schema's session_fingerprint parameter also documents the concurrency guard, so the description doesn't need to repeat that. It doesn't mention side effects on playback, but the annotation covers the destructive nature.

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?

A single sentence that front-loads the action and resource, then adds the crucial differentiator about the toggle-only API. Zero waste, no repetition of schema details, and the most decision-relevant information comes first.

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 simple setter with a full output schema and 100% parameter coverage, the description is nearly complete. The only gap is that it doesn't explicitly state the effect of expected_before (e.g., that the write will fail if the current state doesn't match), but the schema's parameter description covers that. The description plus schema plus annotations together give an agent everything needed to call this correctly.

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 100%, so the schema already documents all three parameters: loop_mode, expected_before, and session_fingerprint. The description adds the high-level intent ('Set Pattern or Song loop mode') but doesn't add meaning beyond the schema's own descriptions, which are already clear. Baseline 3 is appropriate when the schema does the heavy lifting.

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 ('Set'), a specific resource ('Pattern or Song loop mode'), and a key differentiator: it avoids exposing FL's toggle-only API. This clearly distinguishes it from other transport/set tools like fl_set_playing or fl_set_write_mode, and tells the agent exactly what state it will produce.

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 implies when to use it: whenever the agent needs to set an absolute loop mode rather than toggle it. It doesn't explicitly name alternatives or exclusions, but the phrase 'without exposing FL's toggle-only API' signals that this is the safe, absolute setter among transport controls. Sibling names like fl_set_playing and fl_set_write_mode provide context, but the description itself could have been more explicit about when not to use it.

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