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

With no annotations present, the description carries the full behavioral burden. It usefully discloses the auth requirement, that the payload is returned decrypted, and that access is governed by owner+privacy rules — real behavioral context — but says nothing about side effects, rate limits, or error behavior for a tool that exposes sensitive session data.

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 sentence that front-loads the auth requirement, then the action, then the return contents. No filler and nothing buried.

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, so the description correctly compensates by listing the returned payload fields, and it covers the auth and access-control model. For a one-parameter read tool this is close to complete, with only error/edge-case behavior left unspecified.

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 there is a single well-documented 'id' parameter, so the schema does the heavy lifting. The description's 'by ID' adds no detail (format, source of the ID) beyond what the schema already provides, making the baseline 3 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 gives a specific verb and resource ('Fetch a vault session by ID') and even enumerates the returned payload fields (cookies, fingerprint, urls, storage), which clearly separates it from vault-list-sessions and vault-get-revisions. It stops short of naming a sibling explicitly, so sibling differentiation is implied 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?

The '[Auth Required]' prefix signals a precondition, and 'by ID' implies this is the singular-lookup path, but the description never says when to choose this over vault-list-sessions or vault-get-revisions. Usage is inferable from context rather than stated.

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