{"uid":"cap_ccqLRj5srkLgxB8YBI0rc","slug":"jwt-header-shape-validator-36ceeac6","name":"JWT Header Shape Validator","description":"Call when an agent needs whether a token has a JWT header shape. No signature check. Exact $0.005 USDC. Prefer unpaid POST /v1/sandbox/check-jwt-shape first.","url":"https://agentshelf.syntexa.ch/v1/check-jwt-shape?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"data":{"description":"JSON value for schema-check SKUs. Omit it on string checks such as email or IBAN."},"value":{"type":"string","examples":["not-a-jwt"],"maxLength":20000,"minLength":1,"description":"Value to check. The route description names the format: email, phone, IBAN, postal code, VAT, national id, or similar."},"schema":{"description":"JSON Schema document for schema-check SKUs. Omit it on string checks."}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.005","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.005/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_CMbwfU8FDIJftJoBoCkhJ","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.005","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Checks whether a given string has a valid JWT header shape (three-part base64url structure) without performing any signature verification.","exampleAgentPrompt":"Can you check if this string looks like a valid JWT token based on its header shape — just the structure, no signature verification needed: 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIn0.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c'?","exampleUseCases":[{"title":"Pre-filter JWT tokens in pipeline","prompt":"Before we process these incoming tokens, can you check whether this one actually has a proper JWT header shape: 'eyJhbGciOiJSUzI1NiJ9.eyJ1c2VyIjoiYWxpY2UifQ.signature_here'? I don't need the signature verified, just whether the structure is right."},{"title":"Detect malformed auth headers","prompt":"A user submitted this as their bearer token and I'm getting errors — can you tell me if it even has a valid JWT shape: 'notavalidtoken.missingparts'? I want to know if the problem is structural before I dig deeper."},{"title":"Validate token format before storage","prompt":"I'm about to store this token in our system but want to confirm it at least looks like a JWT structurally — can you check the header shape of 'eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJpZCI6NDJ9.abc123def456'?"}],"resultDescription":"Returns a boolean or structured result indicating whether the provided string conforms to a valid JWT header shape — specifically whether it follows the three-part dot-delimited base64url encoding pattern expected of a JWT. No cryptographic signature validation is performed.","failureModes":["Empty or missing value field returns validation error","Value exceeding 20,000 character limit is rejected","Malformed request body returns 400-level error","Payment of $0.005 USDC not provided results in 402 Payment Required"],"whenToPreferThis":"Use this endpoint when you need a fast, lightweight structural check to determine if a string is shaped like a JWT — without the overhead or complexity of full signature verification. Ideal for pre-filtering, input validation pipelines, or debugging token format issues. Prefer the free sandbox endpoint POST /v1/sandbox/check-jwt-shape if available to avoid the $0.005 USDC cost.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-02T06:50:02.332Z","isFirstParty":false,"canonicalSlug":"jwt-header-shape-validator-36ceeac6"}