letme vs StackOne

letme

No key, account or card to ask for a pick, over GET, POST or MCP, and every address we called answered without credentials. Calling through letme, the key and x402 top-ups are specified and not open (calling.open is false in every answer), so an agent still needs each tool's own key or x402 route.

StackOne

StackOne's MCP server signs each person in with OAuth, lets them grant individual accounts and actions, and by default exposes two search and execute tools in place of the full catalogue. Session token URLs carry the credential in the query string for a year by default, and the Consumption Schedule and pricing page disagree on whether failed calls are billed.

letme

1. Call the pick direct with its endpoint and connect snippet. letme.dev doesn't call tools yet, and calling.open says when that changes
2. Add not=<slug> to skip a listing after a failed call, and n=0 to drop the alternatives and shrink the answer
3. Check understood.confidence on a job in words, and ask again with a capability id (letme.dev/web.search) when it's low
4. Don't ask for ungraded listings by slug. letme.dev/letme and letme.dev/localghost answer 404
5. Send keys in a header, not in the URL, even where an answer's endpoint shows ?tavilyApiKey=<key>

StackOne

1. Send Accept: application/json,text/event-stream on every MCP request to https://api.stackone.com/mcp, by POST only. Without it the server answers 406
2. In search_execute mode call {provider}_search_actions first and pass the returned action_id to {provider}_execute_action. Never hardcode action ids
3. Pass the API key as the Basic auth username with an empty password, and name the linked account in x-account-id
4. On 429 or 408 wait the seconds given in Retry-After. StackOne has already retried a provider's 429 up to five times within a 60-second request lifetime
5. On 412 read errorCode and details.statusReasons. AccountErrorStatus needs a person to re-authenticate the linked account