Create a sandbox Item (public_token -> access_token in one step)

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

With no annotations, the description carries the disclosure burden. It reveals the multi-step behavior (two API calls), the side effect (access_token stored in server vault), and the return artifact (item_id). It does not cover idempotency or failure behavior, but the important state-changing effects are named.

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 four tightly packed sentences, each earning its place: the core flow, the side effect/return value, the institution list, and the username guidance. It is front-loaded with the main purpose.

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 output schema, it adequately communicates the return value (item_id) and the state change (stored access_token), plus defaults for institution and usage examples. The unsupported custom_user_json reference is a gap in accuracy, but overall the agent can execute the tool safely.

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?

Because schema coverage is 100%, the baseline is 3. The description adds value by mapping sandbox institution IDs to names and explaining username scenarios, but it also references custom_user_json, which is not a declared parameter in the schema, making the guidance partly misleading.

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 opens with a specific verb-resource pair: creates a test Item without Link. It distinguishes itself from siblings like plaid_link_token_create and item management tools by explaining it performs the public-token-to-access-token exchange in one step.

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?

It clearly says this is the no-Link sandbox creation route and that the returned item_id is consumed by every other tool, so an agent knows when to choose it. It does not explicitly enumerate exclusions, such as production use, but the sandbox-only framing makes the intended context clear.

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