Test the financial API contract before evaluating the agent answer. Verify record types, units, identity, freshness and missing-data states; then test pagination, repeated updates and authorization boundaries. Every case should preserve its input, expected result and observation. These are proposed application tests rather than Bluwhale API performance results.
This financial agent API developer checklist provides ten contract cases and a small missing-balance example. The cases specify what an application should preserve or reject before a model receives financial context. They are illustrative test requirements, not Bluwhale endpoint definitions or results from an API benchmark.
Define the response contract
Choose one read-only task, such as explaining the included balances for two accounts. Define the required identity, amount, currency, balance type, source observation time and coverage state. State what a successful output means before evaluating the wording of an agent answer.
Keep the provider response and your normalized record as separate contracts. A valid provider response can still expose an incorrect application assumption about units, nulls or identity. Test the transformation independently so a failure can be attributed to the source response, adapter or downstream interpretation.
Use synthetic records or a supported sandbox and record its version. MX's official testing documentation is one provider-specific starting point [3]. The field names in the example below are local fixture labels; they do not document a Bluwhale route, SDK or response schema.
Run ten API contract cases
For each case, preserve the input condition, expected contract outcome and actual observation. Define pass, fail and unknown before a run. If the environment cannot exercise a case, mark it untested rather than interpreting the absence of an error as a pass.
Proposed test conditions. No production request or money movement is required. Expected outcomes belong to the application contract; they are not vendor endpoint names, response codes or observed results.
For API01, choose an explicit decimal and scale rule. For API04, retain the original currency with each amount; a conversion requires a stated source, time and transformation. For API05, compare the source observation age with the task's limit rather than judging freshness from the request time alone.
API08 and API10 require inspection of the protected read or tool boundary. The model's response is a separate observation. A system that says access is denied while still returning a protected record has not passed the contract case.
Keep missing balances separate from zero
Use account A with a known balance of USD 100 and required account B with an unavailable balance. The included value is 100 with partial coverage. The complete combined balance is unknown. Replacing B with zero would change the meaning of the data while making the arithmetic appear to work.
Preserve the known amount without overextending the conclusion. A useful answer can say that account A contributes 100 and account B is missing. It should not say the user has 100 across both accounts. If B is later retrieved as a verified zero, the coverage and value can be updated as a new observation.
The same distinction applies when a request times out or returns an error. Retain unavailable as a state, along with the evidence needed for retry or review. Do not fill a failed financial-data request with a plausible generated number.
Reconcile updates before creating context
Test pagination completion before representing a retrieved set as complete. If required pages stop early, preserve the incomplete state and use the documented recovery behavior for the selected provider. One successful page does not establish full retrieval.
Then replay the same update. The application should retain one effective record according to the chosen identity and version rule. Plaid's Transactions documentation describes synchronization with added, modified and removed records [1]; use the applicable provider model instead of treating every notification as a new transaction.
After a correction, verify both the current calculation and its trace. The earlier observation can remain in the audit record without being added to the current total. Keep record reconciliation test results separate from the later question of how an agent explains the change.
Verify denied reads and tenant boundaries
Revoke the credential or grant relevant to the restricted read, then inspect the actual protected request. Preserve the timing and effective scope of the denial. OAuth RFC 7009 defines token revocation behavior, but a successful revocation response alone does not demonstrate every access path, cached response or scheduled job has stopped [2].
For the tenant-boundary case, use synthetic identities and an account outside the current subject's grant. Verify that the protected response is withheld. Record which component authenticates the subject, resolves the account scope and enforces the decision.
Avoid reducing the test to a single invented status code. The correct response and propagation behavior depend on the documented product and contract. The acceptance question is whether unauthorized data can be returned through the boundary in scope, with sufficient evidence to reproduce the finding.
Retain evidence and test the agent separately
Keep the case ID, fixture version, environment, response-contract version, account scope, request and source times, expected outcome, observed outcome and protected trace reference. Store the failure rationale with that record so another engineer can reproduce it.
After the API contract passes, test how the agent interprets the resulting context. Does it preserve partial coverage, cite the correct record and respect the allowed operation? Those are agent-behavior questions. They complement the API cases without turning a valid response into proof of a correct final decision.
Bluwhale's developer offering is a place to scope the financial context and infrastructure required for a workflow [4]. Verify the actual access and documentation before turning this checklist into a product-specific tutorial. The checklist remains usable as a contract specification without inventing live API functionality.
Continue with related resources
- Test the agent behavior after validating its inputs
- Define and revoke agent access
- Choose the data sources
Frequently asked questions
What belongs in an AI agent API developer checklist?
Include response types, units, account identifiers, required fields, freshness, pagination, update reconciliation and access decisions. Each case needs a defined input and expected result so another engineer can reproduce the conclusion.
How is API contract testing different from testing an AI agent?
Contract testing checks what the data boundary returns and permits before the model uses it. Agent testing checks interpretation, instruction handling and tool behavior. A valid response contract does not prove a safe final agent decision.
Should a missing account balance be treated as zero?
No. Preserve missing or unavailable as a separate state. An actual zero is a financial observation. An incomplete response cannot establish a complete total even when the included records sum correctly.
How do I test mixed currencies?
Keep each quantity and currency together. Require an explicit conversion source and time before producing a common-currency total. The fixture should fail a calculation that adds unlike units without that transformation.
What should happen when pagination is incomplete?
Keep the result visibly incomplete until the required pages or update sequence are reconciled. Test the documented recovery path for the selected provider rather than assuming that one page represents all records.
Does an OAuth revocation response prove every access path stopped?
No. Check the effective behavior of the protected read and document propagation and cached access separately. RFC 7009 concerns token revocation; the response alone is not an end-to-end test of every authorization boundary.
Can these tests run without real financial accounts?
Yes, the proposed cases can be specified with local fixtures and a provider sandbox where available. The example records are illustrative. A later production-readiness decision still needs evidence for the actual environment and required accounts.
What evidence should a failed API case retain?
Keep the case and fixture versions, environment, source and request times, expected output, observed output and protected response reference. Record the failure rationale while excluding credentials and personal records from public examples.
Sources and methodology
Official public sources reviewed October 18, 2026. This is a selective documentation review with an original illustrative evaluation method. The examples are not observations from completed provider tests. Bluwhale publishes this guide and is included where relevant. No comparative performance ranking is reported.