Broadcast a message to all sessions

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

With no annotations, the description carries the full behavioral burden. It discloses the core action (broadcast to all sessions) and the read counterpart, but it does not mention whether messages are persistent, if there are limits, or what the return behavior is. For a simple fire-and-forget write, this is adequate but not deep.

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 two tight sentences, front-loading the action in the first sentence and providing a concrete use case in the second. There is no filler, and every clause earns its place.

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 2-parameter tool with no output schema and no annotations, the description covers the purpose, target audience, and usage context. It does not mention response values or error cases, but these are unlikely to be critical for a broadcast operation and the tool's simplicity lowers the bar.

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 input schema already describes both parameters fully ('Your own session name' and 'Message body') with 100% coverage. The description adds no parameter-level nuance beyond what the schema provides, so the baseline of 3 is appropriate.

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 uses a specific verb 'Post' and clearly defines the resource as 'a message visible to every session', which distinguishes it from the targeted bus_send and read-only siblings like bus_peek/bus_receive. The explicit mention of 'via bus_read_broadcasts' also anchors it in the API family.

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 explicitly says 'Use for global announcements' and gives concrete examples ('deploying now', 'main is frozen'), which tells an agent exactly when to choose this tool. It does not name the targeted alternative (bus_send) or state when not to use it, but the global-announcement framing makes the intent clear.

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