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

Annotations cover only the safety profile (readOnly/non-destructive/closed-world), and the description adds substantial behavior beyond that: the exact entry shape, the `{ connection: id }` naming convention, and critically the semantics of unusable logins — that needs_reauth/expired/logged_out sessions are not lost, that a run pauses with a link, and that re-auth restores the same id. This is context an agent cannot derive from annotations or the empty schema.

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?

Front-loaded with what is listed, then the usage directive in bold, then the recovery semantics. It is longer than typical, but nearly every sentence carries actionable instruction (id naming, re-auth behavior, sibling routing) rather than 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?

With no output schema, the description compensates by enumerating the returned fields and explaining how each is meant to be used, and it covers the full lifecycle an agent will hit (usable vs. needs_reauth/expired/logged_out). Nothing needed to call it or interpret its result is missing.

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 tool takes zero parameters, so the baseline is 4. The description's field enumeration ('id', site, account, usable, timestamps) describes return values rather than inputs, which is still useful but not strictly parameter semantics.

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?

States a specific verb+resource ('List the saved logins this account already holds, one entry per login') and enumerates the returned fields, so an agent knows exactly what it gets. It is clearly distinguished from the sibling writers (add_connection, delete_connection) by naming their roles explicitly.

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?

Gives direct when-to-use guidance ('Call this before any task that needs a login, and again whenever you come back to one later') plus an exclusion ('do not ask the user to sign in, just run the script') and a preference rule ('Prefer the login you used before over a new one'). It also routes to the two alternatives, add_connection and delete_connection, with the condition that selects each.

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