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 the concrete consequence the agent needs: the journey's steps, emails included, run for the contact immediately. That explains why the operation is destructive and irreversible in a way the hints alone do not. It still omits what happens for paused/draft journeys or on re-enrollment.

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 front-loaded sentence with no filler; the side effect is stated before the reader can stop. The second clause ('its steps, emails included, then run for them') is slightly telegraphic but still earns its place by implying the email blast.

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 three-parameter destructive action with no output schema, the description covers the core action and consequence. It leaves open error/edge behavior (paused or draft journeys, duplicate enrollment, what is returned), which an agent would need before confidently calling it.

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 every parameter carries its own description, including the non-obvious confirm gate. The description adds nothing about individual parameters beyond the word 'one' implying contactId is singular. Baseline 3 is appropriate when the schema does the work.

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 and resource with scope: 'Adds one contact to a live journey now.' The qualifier 'live' implicitly separates it from test/draft journey tools and 'one contact' fixes cardinality. It stops short of naming a sibling explicitly, so differentiation is inferred rather than stated.

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?

There is no when-to-use or when-not-to-use guidance, and no alternative tool is named. 'Now, as the inbox's Add does' hints at immediacy but gives the agent nothing to route on versus test_journey, publish_journey, or list_journey_people.

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