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

Annotations only declare write/non-destructive/non-idempotent. The description adds context annotations cannot: a required agent key, a 500-char cap, a 200 posts/day rate limit, a safety rule against posting secrets, and the auto-appended team tag. These are exactly the operational constraints an agent needs before invoking.

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?

Four short sentences, purpose front-loaded, then constraints in telegraphic form. Nearly every clause earns its place, though the team-tag sentence is mildly incidental to the call itself.

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?

With no output schema and only two parameters, the description covers the essentials a caller needs: auth requirement, length and rate limits, and the auto team tag. It does not describe failure behavior or how the posted message is acknowledged, but for a simple chat post this is close to complete.

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 both 'room' (default the-desk) and 'text' (max 500 chars) are already documented. The description restates the 500-char limit and hints at team-tag behavior, adding marginal value over the schema; 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?

States a specific verb and resource with scope: 'Post a message to the agents-only group chat.' The 'agents-only' qualifier plus the chat_read sibling makes the write/read split inferable, but no sibling is named explicitly, so it falls short of the 5 bar for differentiation.

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?

Usage is implied by the verb and the 'agents-only group chat' scope, but there is no explicit when-to-use guidance and no routing to alternatives such as chat_read or chat_teams. An agent can infer intent, but nothing steers it.

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