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

With no annotations, the description carries the full burden and does so well: it discloses exponential backoff (2s initial, 1.5x, 30s max) with jitter, terminal states, the auth prerequisite/setup needed before the tool can be called, and the pending behavior via the timeout parameter. This goes well beyond the structured fields.

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?

The description is moderately long but every section earns its place: core behavior, agent workflow, terminal states, pre-poll rendering steps, and access requirements. It is front-loaded with the most important behavioral information and structured in clear paragraphs.

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?

Given no annotations and no output schema, the description covers what an agent needs to invoke this tool correctly: when to call it, what prerequisite action to take, how to present the challenge, what terminal states mean, and the auth barrier. Nothing essential is missing for a polling tool of this complexity.

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%, so the schema already documents both session_id and timeout_seconds thoroughly. The description reinforces session_id's origin ('returned session_id') and the retry behavior on timeout, but it does not add significant meaning beyond the schema. Baseline 3 is 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?

States a specific verb and resource: 'Poll a 2FA session until the user completes the challenge.' This clearly distinguishes it from siblings like start_2fa (which starts the challenge) and get_2fa_status (which likely returns a one-time status). The scope is unambiguous.

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?

Provides explicit sequencing: call after start_2fa with the returned session_id, present the challenge via render_auth_link or sms_message before polling, and restart with start_2fa if the state is 'expired'. Also names an exclusion: 'start_login does NOT open this tool.' This is strong when-to-use/when-not-to-use guidance.

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