ACTION_PLAY_MEDIA

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

With no annotations, the description carries the full burden and does well: it enumerates the output variables (play_success, play_error, play_completed, play_duration_ms), clarifies that play_success only means playback started, and describes how loop=true interacts with timeout_ms (play_completed=false). It does not describe failure conditions for bad paths or unsupported formats beyond the play_error variable.

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 core purpose is front-loaded, but the body is a run-on chain of clauses with a duplicated period ('。。') and the output list wedged mid-paragraph. Every sentence earns its place content-wise, yet the ordering and punctuation could be tightened considerably.

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?

There is no output schema, and the description compensates by naming all four return variables and their semantics. With 7 parameters at full schema coverage, the remaining gaps (require/on_error/output_var behavior) are documented in the schema itself, so the definition is essentially complete for correct invocation.

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 100%, so the baseline is 3, but the description adds real meaning beyond the schema: the loop/timeout interaction and the distinction between 'started' and 'completed' are not derivable from the parameter docs alone. It also reiterates ${var} interpolation for string parameters, which is already in the schema.

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: plays a local media file, audio-only, and blocks until playback finishes or times out. An agent can immediately tell what it does. It does not explicitly distinguish itself from the sibling ACTION_MEDIA_CONTROL, so it stops short of a 5.

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?

Explains the execution model clearly: it blocks, resumes only on completion or timeout, and stops playback when the timeout fires. That is enough to know when this node fits in a workflow. No explicit when-not guidance or named alternative (e.g. ACTION_MEDIA_CONTROL) is given.

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