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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the safety profile is covered; the description still adds real value by defining the blast radius ("revokes that session's access", does not remove friendship, does not sign out Desktop) and noting it returns refreshed state. It stops short of stating auth requirements or what happens to the counterparty's view, so not a 5.

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?

Three tight sentences: what it is, what id means and what the call does, then the alternative routing. No filler, and the sibling disambiguation is placed at the end where it guides the agent after the core purpose is established.

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 single-parameter destructive mutation with full annotation coverage, the description covers identity, effect, effect boundaries, and alternatives; the only omission (exact shape of the refreshed state) is acceptable given no output schema and an explicit note that state is returned.

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?

Only one parameter, and the schema already carries a 100%-covered description plus a UUID format/pattern. The prose restates the same meaning ("pending or active collaboration involving this account") without adding new constraints, so the 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 — revoking a collaboration session identified by id — and immediately delimits scope: it does not remove a friendship or sign out Desktop. It names the two sibling tools (end_collaboration, decline_collaboration) it could be confused with, so an agent can discriminate without opening schemas.

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?

Explicitly routes the model elsewhere: "Models should use end_collaboration" for the general case, and "decline_collaboration is for refusing an incoming invitation." It also states the trigger context (app-only adapter for the panel's End session button), leaving no inference needed about when this applies.

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