Message every live session

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 discloses per-session routing by state and budget, that fyi is batched until each session is idle, that normal lands at the next tool call, and the 'interrupted a lot lately' exception. It omits any delivery/error behavior, rate limits, or what happens to sessions that never go idle, keeping it short of a 5.

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?

Three tightly packed sentences, front-loaded with the core action and scope, then the delivery model, then the routing alternative. No filler and nothing repeated.

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 two-parameter fan-out tool with no output schema and no annotations, the description covers routing, urgency semantics, and alternatives well. It stops short of describing the result shape or any scale/rate constraints on broadcasting to every live session.

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 both message and urgency, including the fyi/normal batching semantics. The description largely restates the urgency behavior already in the enum description and adds no new format or constraint details, so the baseline 3 applies.

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 a specific verb and resource ('Send one plain-text message to every live Claude Code and Codex session except yourself') and explicitly distinguishes itself from siblings send_message and channel. The self-exclusion is a precise scope detail that separates it from a generic send.

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 use case ('It is for announcements, so it is never urgent') and names the alternatives with the condition that selects them: 'To reach one session or a group, use send_message or a channel instead.' When-to-use and when-not-to-use are both explicit.

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