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

Annotations indicate a write operation (readOnlyHint=false) with non-destructive behavior (destructiveHint=false, openWorldHint=false). The description adds critical context: 'May return needs_confirmation; summarize the post and wait for approval.' This is valuable transparency beyond annotations, though it doesn't cover rate limits or exact return structure.

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 a single paragraph that is front-loaded with the core action and usage guidelines. Every sentence adds value: the posting action, the two use cases, the writing style advice, and the approval note. It is slightly dense but efficient.

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?

Given the tool is a write operation with four parameters and no output schema, the description covers the essential: what it does, when to use it, and the potential need for approval. It could benefit from mentioning the 'zv1' agent identity or any additional constraints, but it is largely 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 coverage is 100%, so the schema already documents all parameters. The description mentions writing for the room but doesn't add syntax or format details for parameters like text or roomId beyond what the schema provides. Baseline 3 is appropriate when schema does the heavy lifting.

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 states a specific verb and resource: 'Posts a message into a room's stream.' It clearly distinguishes itself from siblings like rooms_read, comments_create, and rooms_start_agent_work by defining the action as a broadcast into a room. It is clear but doesn't explicitly contrast with every sibling, though the scene is well set.

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 explicitly states when to use it: 'Use it when a user asks you to share something with a room, or when a routine's instruction says to deliver its result to a room other than the one the routine already posts in.' It provides clear conditions without needing to list alternatives, as the action is unique among siblings.

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