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

With no annotations, the description carries the full burden, and it usefully discloses that authentication is required and outlines the payload envelope shape. However, for a mutation it says nothing about what creation produces (an ID?), whether sessions can be overwritten, or how the privacy default behaves at creation time.

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 tight sentences with the auth prerequisite front-loaded and the payload envelope following. There is minimal waste, though the envelope restatement duplicates schema content rather than earning its place.

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?

There is no output schema and no annotations, so the description must carry behavioral weight, which it only partly does. It covers the what and the payload shape but leaves the mutation's result and reversibility unaddressed, making it minimally adequate rather than complete.

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%, so the schema already documents 'data', 'label', and 'privacy'. The description's envelope listing essentially repeats the 'data' field's own description, adding no new semantics beyond what the schema provides. Baseline 3 is appropriate.

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 and resource ('Create a new vault session') plus scope ('under the agent's owner'), which clearly separates it from read-only siblings like vault-get-session and vault-list-sessions. It does not, however, differentiate itself from the nearest sibling vault-clone-session, which is also a creation operation.

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 '[Auth Required]' tag supplies a prerequisite, and 'Create a new vault session' implies the usage context. But there is no explicit guidance on when to use this versus vault-clone-session or vault-update-session, so selection among the vault-write siblings is left to inference.

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