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

Annotations already indicate the operation is not read-only, not idempotent, and not destructive. The description adds the 'allowlisted' and 'assisted session' context, but it does not disclose what navigation entails, such as whether the current page is replaced, whether portal state is reset, or whether an active session is required. With annotations present the bar is lower, but the description still contributes little behavioral detail beyond what is already stated.

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 description is a single, compact sentence that front-loads the action and embeds the portal list efficiently. There is no filler or redundant restatement of the title.

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 simple two-parameter tool with an output schema, an enum constraint, and annotations, the description is mostly adequate. The main gaps are the lack of explicit session prerequisite and sequencing context relative to sibling tools like start_browser_session and prepare_portal_fill. It is functional but not fully self-contained.

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 description coverage is 100%, and both sessionId and portalId already have clear descriptions, including examples and an enum for portalId. The description essentially repeats the portal enum values rather than adding new semantic meaning, so the baseline of 3 applies.

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 uses a specific verb ('Navigate'), names the resource ('the assisted session'), and enumerates all allowlisted portal IDs. It clearly distinguishes this from session lifecycle siblings like start_browser_session and end_browser_session by targeting an existing session.

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 implies usage context: it navigates an already-started assisted session to an official portal, and the sessionId requirement reinforces this. However, it does not explicitly state when to use this tool versus alternatives such as prepare_portal_fill or get_self_serve_portal, nor does it name any exclusions.

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