{"uid":"cap_d_WXdYyPGbrT4fACE8d5M","slug":"dev-reference-http-header-lookup-3bf34029","name":"Dev Reference – HTTP Header Lookup","description":"Explain an HTTP header: request or response, purpose, security notes, and its IANA registration status.","url":"https://dev-reference.x402tookit.com/http-header?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["name"],"properties":{"name":{"type":"string","description":"Header field name, for example Strict-Transport-Security"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"asOf":{"type":["null","string"]},"name":{"type":["null","string"]},"source":{"type":["null","string"]},"purpose":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"summary":{"type":["null","string"]},"verdict":{"type":["null","string"]},"degraded":{"type":["boolean","null"]},"direction":{"type":["null","string"]},"reference":{"type":["null","string"]},"disclaimer":{"type":["null","string"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"registered":{"type":["boolean","null"]},"securityNote":{"type":["null","string"]},"registryStatus":{"type":["null","string"]},"structuredType":{}}}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.02","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":"$0.02/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_kvhb3WKXTY3juAQUrycWM","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.02","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Returns the purpose, direction (request/response), security notes, and IANA registration status for a named HTTP header field.","exampleAgentPrompt":"What does the Strict-Transport-Security HTTP header do — is it a request or response header, what's its purpose, any security notes, and is it officially registered with IANA?","exampleUseCases":[{"title":"Security audit of response headers","prompt":"I'm reviewing our API's response headers — can you explain what the X-Content-Type-Options header does, whether it's a request or response header, and flag any security concerns?"},{"title":"Developer documentation research","prompt":"I'm writing docs for our HTTP API — what's the purpose of the Accept header, what direction is it used in, and is it formally registered with IANA?"},{"title":"Debugging unknown header behavior","prompt":"I keep seeing a Forwarded header in our server logs and I'm not sure what it does — can you look it up and tell me its purpose, direction, and registration status?"}],"resultDescription":"A structured record containing the header's canonical name, direction (request or response), a plain-English summary of its purpose, a security note highlighting any risks or best practices, its IANA registration status (boolean and registry status string), a reference URL, and metadata such as the data freshness date and whether the result is degraded.","failureModes":["Unknown or non-standard header name may return null fields or unregistered status","Misspelled header name may produce empty or degraded result","Very new or experimental headers may lack IANA registration data","Network or upstream lookup failure may return a degraded flag with partial data"],"whenToPreferThis":"Use this endpoint when an agent or developer needs authoritative, structured information about a specific HTTP header — including its semantics, direction, security implications, and IANA registration status — rather than a free-text web search. Ideal for documentation generation, security audits, and developer tooling where structured, reliable metadata is required.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-29T13:08:06.738Z","isFirstParty":false,"canonicalSlug":"dev-reference-http-header-lookup-3bf34029"}