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

Annotations already declare read-only, idempotent, non-destructive, open-world behavior, so the description only needs to add what they don't say. It does add real context: streams are account-scoped, there is a hard limit, exceeding it produces a 429, and the payload shape (chatId, opened, last seen).

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 dense sentence, front-loaded with what is being listed, then the limit/429 consequence, then the fields. The trailing 'GET /chats/streams' is marginally redundant but cheap and informative.

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, the description usefully enumerates the returned fields and explains the limit semantics, which is what an agent needs to interpret the result. It is not missing anything essential for a zero-required-parameter read call.

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% for the single optional 'email' parameter, and the description never mentions it — including the important nuance that it is only needed when the token spans multiple accounts. Baseline 3 applies since the schema carries the parameter on its own.

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 the resource and its scope precisely: 'the chat streams open on an account right now', with the returned fields and the backing endpoint. It is clearly a report of currently-open streams rather than a general chat listing, though it does not explicitly contrast itself with siblings like muse_list_chats or muse_get_chat.

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 supplies concrete context for when the tool matters — checking usage 'against its limit' before a chat call fails with 429. There are no explicit exclusions or named alternatives, so it stops short of a 5.

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