simplepractice_verify_sign_in_pin

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

Annotations already declare destructiveHint=true, idempotentHint=false, and openWorldHint=true, so the safety profile is covered. The description usefully adds 'Single-use,' which reinforces the non-idempotent nature of the PIN, but it says nothing about what a 'session' means, whether it mutates server state, or any expiry/auth constraints. No contradiction with the annotations.

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?

Two short sentences with the action and scope front-loaded and the single-use constraint appended. Every clause earns its place; 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?

For a no-output-schema tool, the description conveys both the input semantics (6-digit PIN, email) and the outcome (a session). What the returned session looks like and its lifetime are unstated, but the annotations carry the mutation/safety context, so the gap is minor.

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 50%: email is documented in the schema, while pin has only a regex pattern and no description. The description compensates minimally by restating '6-digit PIN', which aligns with the schema pattern but adds no new format or source information. Baseline 3 is appropriate given the schema does most of 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?

States a specific verb+resource (exchange a 6-digit PIN for a session) with a clear scope qualifier ('for practices that email a code instead of a link'). This cleanly distinguishes it from the sibling verify_sign_in_token, which handles link-based sign-in.

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 phrase 'for practices that email a code instead of a link' tells the agent the exact condition under which this tool applies rather than its siblings. It stops short of naming the alternatives (request_sign_in_link, verify_sign_in_token) or stating when not to use it, so it is clear context but not fully explicit routing.

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