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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is covered. The description adds meaningful context beyond that: it reassures that the tool 'Sends nothing', and discloses validation behavior ('Offer terms with a dash or a word the emails may not use are refused'). It does not describe what is returned or whether changes are reversible.

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 purpose is front-loaded in the first clause and each following sentence adds real information (validation, no-send guarantee). The middle enumeration is a long run-on sentence that is dense but every element maps to a distinct parameter, so little 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 7-parameter mutation tool with no output schema, the description covers all fields, validation rules, and the side-effect profile. The only gap is that it says nothing about the result/confirmation returned after a change, though with no output schema that burden is reduced.

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?

Although schema coverage is 100%, the description materially enriches it: character limits (400 for offerTerms, 200 for pricingDetails), the semantics of each enum value ('link' asks for a link, 'mention' asks for a brand mention only; 'default' is one-sided vs 'exchange' mutual), and the constraint that pricingDetails is the only figure the emails may quote. This is well beyond what the schema states.

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 states a specific verb ('Change') and resource ('how first emails are framed'), then enumerates the exact settings touched (offerTerms, offerInFirstTouch, outreachGoal, emailStyle, pricingDetails, fromName). This makes it clearly distinguishable from sibling setters like set_profile, set_run_settings, and set_sending, which govern different domains.

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 concrete invocation rule ('Pass only the fields to change') and clarifies per-field behavior (whether the offer goes in the first email or is held for the reply). It does not name alternative tools or state when this tool should not be used, so it stops short of explicit routing guidance.

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