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

The description is otherwise unusually rich — it discloses transactional behavior ('in one transaction'), collision handling ('what collides ... stays with the guest'), scope limits ('only what the guest still has') and the CSRF/bootstrap precondition. However, it states 'A repeat does no harm (it moves zero),' which is idempotent semantics, while the annotations declare idempotentHint=false — a real conflict that could mislead retry logic.

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 core action is front-loaded and the sentences are dense with information rather than filler. It is slightly convoluted with parenthetical asides ('(the SDK claim)', '(it moves zero)') and untranslated domain nouns, but no sentence is wasted.

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 mutation with no output schema, it covers preconditions, atomicity and collision behavior well, but says nothing about the response (counts of moved items are only implied by 'it moves zero') or error cases such as an expired/absent guest session. Enough to invoke, not enough to interpret the result.

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?

There is one parameter with 100% schema description coverage ('Token edm_… of the guest.'), so the schema already carries the meaning. The description only reaffirms the 'edm_…' token origin ('what the guest edm_… created'), adding nothing about format, lifetime or where to obtain it.

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 a specific verb and resource set: it brings guest-created 'Salvas, Alertas and Vigias' plus purchased documents into the session account. The domain terms are unusual but the operation is unambiguous. It does not explicitly name or distinguish itself from potential siblings (e.g. account_tracking, list_saved), so it stops short of a 5.

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 gives a clear trigger context: 'Requires the bootstrap/CSRF of this browser; the page does it right after sign-in,' which tells the agent when this runs and what precondition must hold. What is missing is any explicit exclusion or named alternative route for the same goal, so it does not reach 5.

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