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

Goes well beyond annotations (readOnlyHint/idempotentHint/destructiveHint) by disclosing that unsubscribeFooter is off by default and omitted means unchanged, that plainTextEmail is read-only and overrides the footer/tracking, that List-Unsubscribe headers otherwise apply, that pacing continues on next tick, and that there is no Energy charge. Rich, non-obvious behavioral context for a mutation tool.

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?

Front-loaded with the read behavior before the write behavior, and each sentence carries distinct information (footer semantics, plainTextEmail override, non-effects, no Energy charge). Slightly dense with several clauses packed into single sentences, but nothing 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?

Given a complex nested, dual read/write tool with no output schema and 33% param coverage, the description covers behavior, side effects, and read-only fields well. The remaining gap is the nested settings sub-fields (schedule/mailboxIds/dailyLimit), which are left entirely to the schema.

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 low (33%) with a required nested settings object (mailboxIds, schedule, dailyLimit), and the description does not explain those nested fields. It does add semantics for unsubscribeFooter ('adds a visible unsubscribe line; off by default; omit to keep it'), which is genuinely beyond the schema, partially compensating for the gap.

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 (read) and resource (sequence's email sending inboxes, schedule, daily limit, unsubscribeFooter), plus the write mode ('Supply settings to replace sequence preferences'). It explicitly distinguishes from set_sequence_status ('Does not change sequence status') and from send actions ('or send immediately'), so an agent can route correctly without opening the 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?

Clear read-vs-write condition is stated: omit settings to read, supply settings to replace. It also clarifies what it will NOT do (change status, send immediately) and notes paused/disconnected inboxes stay that way. It doesn't name a specific sibling alternative for replacing settings, but the boundary conditions are well covered.

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