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

Annotations already declare destructiveHint=true and idempotentHint=false, but the description adds substantial behavioral context beyond them: remaining main-sequence emails are canceled, the subsequence sends real email from the same mailbox and in the same thread, and off/paused subsequences queue leads rather than rejecting them. It also discloses the shape of the result (who entered, who was skipped and why, who is not a campaign lead), which is the key side-effect information for a destructive move.

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 dense sentences, front-loaded with the action and scope, then the consequences, then the edge cases. No filler, though the long dash-joined clauses make it slightly harder to scan than an ideally structured description.

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 destructive, non-idempotent bulk mutation with no output schema, the description covers side effects, eligibility, limits, and result contents. The remaining gap is small: no mention of permission/mailbox-connection requirements and no clarification of how `start` interacts with an already-paused subsequence.

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%, so the parameters are already well documented, and the description only adds the mutual "by `leadIds` or `emails`" framing plus the 1000 limit. It says nothing about the `start` parameter (now/delay/date), which is the one field whose interaction with a paused subsequence an agent might want clarified. Baseline 3 is appropriate given the schema does the heavy lifting.

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?

"Move leads of the main campaign ... into a subsequence" gives a concrete verb, resource, and direction of movement, and immediately distinguishes the operation from add_leads or list_subsequences. It even names the input modes (`leadIds` or `emails`) and the 1000 cap, so an agent knows exactly which operation is being requested.

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?

The description supplies real selection criteria: leads must be from the main campaign, must already have been emailed, and can enter a given subsequence only once. It also explains the paused-subsequence case, so an agent can decide whether the call is appropriate. It does not compare against siblings such as add_leads or list_subsequences, which keeps it from a 5.

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