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

The only added behavioral context is 'privacy-filtered project metadata,' which is somewhat useful. However, the description does not explain session creation/update semantics, side effects, how expectedVersion affects updates, or idempotency behavior; the annotations already cover the basic non-destructive idempotent hints.

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 short, but it is also malformed and under-specified. This reads as an accidental sentence rather than deliberate concise structuring, so it does not earn credit for effective brevity.

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?

With no output schema, five parameters, and no lifecycle or routing context, the description is completely inadequate for invoking the tool correctly. It does not say what the response contains, how the session progresses, or how this relates to finish_agent_session and execution-status tools.

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 0%, and the description mentions none of the five parameters. Only projectId is vaguely implied by the phrase 'project metadata'; requestText, sessionId, idempotencyKey, and expectedVersion are left entirely undocumented.

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 the verb 'Update' with a garbled noun phrase 'hosted start agent session,' so it never clearly states whether the tool starts or updates a session. It also fails to distinguish itself from sibling tools such as begin_agent_execution, finish_agent_session, or open_project_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?

There is no guidance on when to use this tool, what prerequisites exist, or which alternatives apply. An agent cannot determine whether to call start_agent_session versus the many session- and execution-related siblings.

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