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

No annotations are supplied, so the description carries the full burden, and it discloses meaningful behavior: it is strictly read-only and never refreshes the session, and it names the remediation when the session is invalid. It stops short of saying whether it performs a live network validation or how failures other than expiry are reported.

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 short sentences, front-loaded with the core purpose, followed by the read-only caveat and the recovery path. Nothing is redundant or 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?

For a single-optional-parameter, read-only check with no output schema, the description covers purpose, side-effect profile, and the failure branch. A sentence on the shape of the returned account list or the non-expiry error behavior would make it 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?

The single optional parameter 'notification_message' is fully documented in the schema (100% coverage), so the schema does the work here. The description adds no additional meaning about when to supply it or how it interacts with the expiry result, 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 gives a specific verb and resource: verifying the saved Google Photos session and listing signed-in accounts. It is clear what the tool does, though it never distinguishes itself from the sibling 'list_accounts', which plausibly overlaps on the account-listing half.

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?

It provides a concrete routing rule for the failure path: if the session is reported expired, the user reconnects via start_browser_auth. It does not state the positive case (e.g., call this before other operations to confirm authentication), which is a minor gap.

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