mplay

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

Annotations already declare the operation is not read-only, is idempotent, and is non-destructive, so the safety profile is covered. The description adds nothing beyond that: it does not say whether playback blocks the caller, whether it loops, or what happens if no movie is defined — all material for a playback control tool.

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 front-loaded sentence with zero filler. It is appropriately terse for a zero-argument tool, though the terseness contributes to the missing behavioral context noted elsewhere.

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. However, for a playback control tool the description omits prerequisites (movie must be set up first) and playback behavior (blocking vs. asynchronous, looping), leaving real gaps 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?

The tool takes zero parameters, so the baseline of 4 applies; there is no parameter semantics the description could or should explain.

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 ("Starts playing the movie"), which clearly distinguishes it from siblings like mstop and implicitly from mset. It is clear what the tool does, though it never names the counterpart tool (mstop) or the setup tool (mset) explicitly.

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 when-to-use guidance, no stated prerequisite that a movie must already be defined (e.g., via mset), and no mention of mstop as the counterpart for halting playback. The agent must infer all usage conditions from the name.

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