session_storage

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

Annotations already declare readOnlyHint=true, and the description reinforces this with 'Snapshot' while adding useful behavioral context: the output structure, the current-origin scope, and the timing warning about session idle timeout. It doesn't discuss failure modes or size limits, but the read-only annotation lowers the burden.

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?

Three sentences, each earning its place: the first states what the tool snapshots and returns, the second explains the restoration workflow, and the third gives the timing constraint. The purpose is front-loaded and there is no filler.

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?

Although there is no output schema, the description explicitly provides the return shape as {url, local_storage, session_storage}. It also explains how the output is consumed by session_create, what origin it applies to, and when to call it, making the description complete for an agent to invoke the tool correctly.

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?

The schema already documents the only parameter, session_id, at 100% coverage. The description adds no additional meaning about session_id semantics or valid values, so it stays at the baseline of 3.

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 ('Snapshot') and a precise resource ('the session's localStorage/sessionStorage for the current origin'), and it even names the exact return shape. It also separates this tool's role from cookie handling by explaining it captures the half of login state that cookies can't carry.

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 clear usage context: call it before the session idles out, and feed the result into session_create's 'storage' field to restore logged-in state. It implies a complementary relationship with cookies but never explicitly names session_cookies as the cookie-handling alternative, so it stops short of an explicit when-to-use vs when-not-to-use statement.

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