Message players

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

Annotations already declare this is a non-read-only, non-destructive, non-idempotent write. The description adds context beyond that: omitting `players` broadcasts to everyone online (a real blast-radius detail) and a sound plays only for explicitly named players, implying unreachable/offline names silently miss it.

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?

Two tight sentences, with the broadest-scope behavior (everyone online) surfaced immediately, then the sound caveat. No filler.

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 6-parameter mutation tool with no output schema, the description covers targeting, kinds, and the sound constraint. Missing are delivery failure behavior (unknown/offline names) and whether `format` applies to titles and action bars alike.

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 67%, with enums and defaults documented inline. The description clarifies the `players` omission semantics and the sound restriction, but says nothing about `format`, `subtitle`, or how names vs UUIDs behave — those rely entirely on 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?

The description names specific verbs and resources — chat message, title, action bar text, sound — and states the targeting scope (named players or everyone online). It is clearly distinguishable from generic siblings like run_command, though it never names an alternative 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?

It states the default audience when `players` is omitted and that a sound only plays for named players, which is useful routing context. However, it never says when to prefer this over run_command or world_effect, nor when to choose title vs actionbar vs chat.

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