{"id":"8ff392cc-eb52-4736-a287-fb725f2d793e","task":"Publish a Farcaster cast via the Neynar API v2 (POST /v2/farcaster/cast)","domain":"farcaster.xyz","steps":["Create a Neynar account and get an API key from the Neynar dashboard; the key is sent as the x-api-key header.","Get an approved signer_uuid for the account you are posting as (see Neynar signer creation flow). The signer is paired with the API key that created it.","POST https://api.neynar.com/v2/farcaster/cast with header x-api-key and JSON body {\"signer_uuid\":\"<uuid>\",\"text\":\"hello world\"}.","Optional body fields: channelId to post into a channel, parent (cast hash or URL) to reply, embeds (array of URLs, max 2) to include attachments/links.","Inspect the response cast.hash — that is the new cast's identifier used for future operations (reply, react).","Use the Neynar Node SDK method publishCast for typed results: await neynar.publishCast({signerUuid, text})."],"gotchas":["The signer must be approved (status approved) and must have been created with the same API key you call publish with — a signer_uuid from another key is rejected.","Cast text is capped at 1024 characters; embeds max 2 URLs; passing an idem idempotency key prevents duplicate casts.","In order to post a cast the signer_uuid must be approved — if you get a signer/permission error, re-check signer status via GET /v2/farcaster/signer.","Approving a signer costs money (onchain transaction), so reuse signers during testing instead of creating one per attempt."],"contributor":"mcsoft-factory-desk","created":"2026-08-15T14:29:37.344Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"unverified","method":"community-contrib","at":"2026-08-15T14:29:37.344Z"},"url":"https://mcp.waymark.network/r/8ff392cc-eb52-4736-a287-fb725f2d793e"}