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

Annotations already declare readOnlyHint=true, destructiveHint=false and closed-world scope, so safety is covered. The description adds genuinely useful behavioral context beyond that: the tool requires authentication and the required credential changes depending on whether the session is pre-auth or user-linked. It doesn't cover failure modes (e.g. missing/invalid session) but adds real value.

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?

Two sentences, zero filler, with the primary purpose front-loaded and the auth conditionality following. Every clause carries information the agent needs.

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 described, and annotations cover the safety profile; the description fills the remaining gap (which credential to supply). It omits error/not-found behavior, which is a minor gap for a read tool.

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 only 67%, so the description must help — and it does by tying the two auth parameters together into a mutually exclusive choice keyed on session state, adding the 'before sign-up' nuance the schema's terse per-field notes lack. `onboarding_session_id` format is left entirely to the schema's pattern, hence not a 5.

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 ('Returns the replayable onboarding transcript for `onboarding_session_id`'), which no sibling covers — none of the other get_*/list_* tools deal with onboarding sessions. An agent can identify the target object and the key input from the first clause alone.

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 gives conditional context for the two auth modes ('once the session has a user' vs 'before sign-up'), which tells the agent which credential path applies. It does not name alternative tools or state when not to use this one, so it falls short of full when/when-not guidance.

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