venmo_login

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

No annotations are provided, so the description carries the transparency burden. It discloses the env var fallback behavior and the prerequisite ordering, which is helpful. However, it doesn't describe what 'log in' does internally (e.g., session creation, credential storage, error conditions), leaving some behavioral aspects ambiguous.

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 core purpose. The first sentence is an imperative that clearly states the tool's function, and the second sentence adds the env var behavior without waste. Every word earns its place.

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 login tool with two parameters and no output schema, the description covers the essential aspects: what it does, when it's required, and parameter fallbacks. It doesn't detail session management or post-login state, but given the tool's simplicity, this is reasonably complete.

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 schema description coverage is 100%, with each parameter already detailing the env var fallback. The description adds no new parameter information beyond restating the fallback, so the baseline of 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?

The description clearly states 'Log in to Venmo with your username/email/phone and password' with a specific verb and resource. It also distinguishes from all sibling venmo_* tools by noting it is 'Required before all other operations', making its purpose unmistakable.

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 explicitly says 'Required before all other operations', which clearly communicates when to use this tool. It doesn't mention alternatives or when not to use it, but since it's a login prerequisite, the ordering guidance is sufficient.

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