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

Annotations already flag destructive/non-idempotent/openWorld, and the description adds substantial un-structured detail: login required, permanence, DM returns 400 cannot_leave_dm (do not retry), and the subtle rule that a 404 may mean already-left but must not be treated as success. This is exactly the elevation the annotations cannot supply.

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?

Information-dense and front-loaded with the destructive/permanent nature and error semantics before the alternative and the call chain. The bracketed shorthand style is compact but slightly terse; nearly every clause earns its place.

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 one-param destructive mutation with no output schema, the description covers prerequisites (login), irreversibility, error-code handling, and the recommended alternative plus the sequencing chain — everything an agent needs to invoke it safely.

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% and the single conversationId param is documented, so baseline 3 applies. The description says to 'confirm the group name' first, but the parameter is an id rather than a name, so it adds little param-level meaning and slightly blurs the input type.

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+resource (permanently LEAVE a GROUP conversation) and immediately differentiates from siblings by naming set_conversation_muted as the 'just want quiet' alternative. The agent can tell it apart from other conversation tools without opening a schema.

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?

Explicit when-to-use and when-not: use set_conversation_muted if you only want quiet, set icebreak=false to stop future group pulls (noting old groups still need leaving), and it gives the exact call chain list_my_conversations → confirm → leave. Alternatives and preconditions are all stated.

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