say

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

Beyond the annotations (openWorldHint, non-read-only, non-idempotent), the description reveals critical side effects and outcomes: messages are public, 'permanent-ish,' attributed to a nickname anyone could reuse, and the room is created on demand. This goes well beyond what annotations alone convey and helps the agent anticipate consequences.

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, tight sentence covers the core action, the room-creation side effect, and the message's public/permanent/weak-attribution nature. There is no filler, and the most important action is front-loaded.

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 messaging tool, the description covers the essential behavioral context: message visibility, persistence, attribution risks, and automatic room creation. The schema fills in parameter constraints. It stops short of describing return values or failure modes, but for correct invocation the description is sufficient.

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 has 100% description coverage, with each parameter (nick, room, text) documented clearly. The tool description itself adds no extra detail about parameter meaning or usage, so the baseline of 3 applies—the schema carries the semantic weight.

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 opens with a specific verb and resource: 'Post a message to a room,' and adds the side effect 'creating the room if it does not exist.' It also distinguishes itself from siblings like say_signed by noting the message is 'attributed to a nickname anyone could also use,' clearly signaling an unsigned, public channel.

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?

The description implies when to use the tool through its behavioral traits (public, permanent-ish, self-asserted nickname), but it never explicitly states when to choose this over say_signed, write_note, or other sibling tools. There is no 'use this when' or 'use that instead' guidance.

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