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

Annotations already declare this is a non-readonly, non-idempotent, open-world call, and the description adds genuinely non-obvious behavior: the returned code cannot be redeemed by the calling session and must be handled out of band. It does not say what the call returns (code value, verification URL, expiry) or whether repeated calls invalidate earlier codes, which matters given idempotentHint=false and no output 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?

Three short sentences, front-loaded with what the tool does, followed by the redeemability constraint and the alternatives — no filler. The pointer to an external URL is efficient, though it shifts some necessary detail off-definition.

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 should indicate what the agent receives and must surface to the user (code, verification URL, expiry) — that is missing. The redirect to the skill doc partially covers the procedure but leaves the return-handling step implicit for an auth flow where misuse is costly.

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 coverage is 100% for the single optional client_name parameter, and its on-page impersonation warning is already in the schema, so the description need not repeat it. The description adds no parameter meaning of its own, which is the expected baseline when the schema does the work.

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 names a specific action and object: starting a device code for an additional HTTP client, scoped to an already-authenticated MCP session. It explicitly contrasts this with the host reconnect flow and the HTTP device flow, so an agent can tell it apart from the other bdk_* setup/auth tools without opening a schema.

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 states both the applicable condition (additional HTTP client, existing authenticated session) and the exclusions with named alternatives: host reconnect for initial or expired MCP auth, and the external skill doc for the HTTP device flow. The critical negative guidance — this session cannot redeem the code through a tool — is stated up front.

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