Email login — verify OTP

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

The description discloses the side effect of storing PASETO in the MCP session, which adds meaningful behavioral context beyond the sparse openWorldHint annotation. However, it does not mention potential side effects like invalidating previous sessions or failure behaviors, so transparency is limited but not absent.

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 concise sentences, front-loaded with the action and endpoint, followed by the side-effect. Every word earns its place, and the structure is easy to scan.

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 simple auth tool, the description covers the core action and side effect, but lacks prerequisites (e.g., that auth_email_login_start must have been called) and does not describe the response format since there is no output schema. This leaves some gaps for an agent choosing to invoke the tool.

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 67% (code and ref are described; email only has a format). The description adds no additional parameter semantics, but the schema already provides clear descriptions for required fields. Baseline of 3 applies, with no significant added value from the description.

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 clearly states the tool's action: verify email OTP and log in, with the specific endpoint and the side effect of storing PASETO in the MCP session. This distinguishes it from siblings like auth_email_login_start (which likely initiates login) and auth_wallet_complete.

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 description implies the tool is used after receiving an OTP via email, but it does not explicitly say to use it after auth_email_login_start or provide alternatives. No exclusions are given, so usage context is only implied rather than fully specified.

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