Begin File Transfer Cancellation

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

Annotations already declare readOnly=false, idempotent=false, destructive=false, so the safety profile is covered. The description adds the lease precondition, which is real behavioral context, but leaves the key question open: does calling this actually stop the transfer, or only stage a confirmation that must be resolved separately? For a non-idempotent state-changing call, that ambiguity matters.

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 sentence with no filler, and the precondition is front-loaded as a 'only when' clause. It is efficient, though the terseness borders on under-specification rather than crispness.

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?

An output schema exists, so return values need not be explained. But this is one half of an apparent two-step protocol (begin -> resolve_file_transfer_cancel), and the description never says so; an agent could call it and assume the transfer stopped. For a non-idempotent state-machine step among 37 siblings, that missing linkage is a substantial gap.

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 only one parameter exists, so the schema fully documents session_id. The description adds a meaningful constraint on that parameter — the session must hold an active file-transfer lease — which the schema field text does not say. That is a modest but real value-add above baseline.

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 verb 'Begin' and resource 'cancellation confirmation' are stated, but the phrasing is jargon-heavy: an agent cannot tell from this whether the transfer is actually cancelled or merely queued for confirmation. It also fails to differentiate from the sibling terminal_resolve_file_transfer_cancel, which appears to be the natural completion of this step.

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?

'Only when a file-transfer lease is active on the Session' gives a genuine precondition, which is more than most. However, there is no mention of what to do next (resolve_file_transfer_cancel), what alternative exists if no lease is active, or whether this may be called repeatedly.

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