Link Bank (SimpleFIN)

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

The description claims the tool is idempotent ('Idempotent transactions (dedupe by provider id)'), but the annotations explicitly set idempotentHint: false, creating a direct contradiction. This severely undermines the agent's ability to reason about behavior.

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?

Very concise and front-loaded: first sentence states purpose, then token acquisition, then tool actions, then idempotency, then args and returns. Every sentence earns its place with no fluff.

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 tool with one parameter and no output schema, the description covers the token source, idempotency, side effect (durable URL), initial sync duration, and return values. Minor gap: does not explain what 'import counts' means, but sufficient for an AI.

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 input schema already describes the setup_token parameter with coverage 100%. The description adds value by specifying how to obtain the token (link to website, account steps) and its format (base64), which aids correct usage.

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?

Description explicitly states 'Connect a bank via SimpleFIN Bridge for real-time balances and ongoing transaction sync', clearly defining the verb and resource, and differentiating from sibling tools like finance_import_csv and finance_search_transactions.

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 concrete instructions for obtaining the token ('Get a one-time setup token from bridge.simplefin.org (My Account → generate a token)') and explains that it creates a durable access URL and runs an initial sync. However, it does not explicitly exclude other tools or state when not to use it, which would be helpful.

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