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POST
/
api
/
chat-messages
/
chat
/
id
/
{chatId}
Add a new message to a specific chat via API key
curl --request POST \
  --url https://api.leanmcp.com/api/chat-messages/chat/id/{chatId} \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "role": "user",
  "content": "Hello, can you help me with my project?",
  "metadata": {
    "model": "claude-3-sonnet",
    "tokens": 150
  },
  "fileIds": [
    "f1a83d84-7154-464c-bd19-a9f10e0a067f",
    "f2b94e95-8265-575d-ce2a-b0f21f1b178g"
  ]
}
'
import requests

url = "https://api.leanmcp.com/api/chat-messages/chat/id/{chatId}"

payload = {
"role": "user",
"content": "Hello, can you help me with my project?",
"metadata": {
"model": "claude-3-sonnet",
"tokens": 150
},
"fileIds": ["f1a83d84-7154-464c-bd19-a9f10e0a067f", "f2b94e95-8265-575d-ce2a-b0f21f1b178g"]
}
headers = {
"Authorization": "Bearer <token>",
"Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)
const options = {
method: 'POST',
headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
body: JSON.stringify({
role: 'user',
content: 'Hello, can you help me with my project?',
metadata: {model: 'claude-3-sonnet', tokens: 150},
fileIds: ['f1a83d84-7154-464c-bd19-a9f10e0a067f', 'f2b94e95-8265-575d-ce2a-b0f21f1b178g']
})
};

fetch('https://api.leanmcp.com/api/chat-messages/chat/id/{chatId}', options)
.then(res => res.json())
.then(res => console.log(res))
.catch(err => console.error(err));
<?php

$curl = curl_init();

curl_setopt_array($curl, [
CURLOPT_URL => "https://api.leanmcp.com/api/chat-messages/chat/id/{chatId}",
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "POST",
CURLOPT_POSTFIELDS => json_encode([
'role' => 'user',
'content' => 'Hello, can you help me with my project?',
'metadata' => [
'model' => 'claude-3-sonnet',
'tokens' => 150
],
'fileIds' => [
'f1a83d84-7154-464c-bd19-a9f10e0a067f',
'f2b94e95-8265-575d-ce2a-b0f21f1b178g'
]
]),
CURLOPT_HTTPHEADER => [
"Authorization: Bearer <token>",
"Content-Type: application/json"
],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
echo "cURL Error #:" . $err;
} else {
echo $response;
}
package main

import (
"fmt"
"strings"
"net/http"
"io"
)

func main() {

url := "https://api.leanmcp.com/api/chat-messages/chat/id/{chatId}"

payload := strings.NewReader("{\n \"role\": \"user\",\n \"content\": \"Hello, can you help me with my project?\",\n \"metadata\": {\n \"model\": \"claude-3-sonnet\",\n \"tokens\": 150\n },\n \"fileIds\": [\n \"f1a83d84-7154-464c-bd19-a9f10e0a067f\",\n \"f2b94e95-8265-575d-ce2a-b0f21f1b178g\"\n ]\n}")

req, _ := http.NewRequest("POST", url, payload)

req.Header.Add("Authorization", "Bearer <token>")
req.Header.Add("Content-Type", "application/json")

res, _ := http.DefaultClient.Do(req)

defer res.Body.Close()
body, _ := io.ReadAll(res.Body)

fmt.Println(string(body))

}
HttpResponse<String> response = Unirest.post("https://api.leanmcp.com/api/chat-messages/chat/id/{chatId}")
.header("Authorization", "Bearer <token>")
.header("Content-Type", "application/json")
.body("{\n \"role\": \"user\",\n \"content\": \"Hello, can you help me with my project?\",\n \"metadata\": {\n \"model\": \"claude-3-sonnet\",\n \"tokens\": 150\n },\n \"fileIds\": [\n \"f1a83d84-7154-464c-bd19-a9f10e0a067f\",\n \"f2b94e95-8265-575d-ce2a-b0f21f1b178g\"\n ]\n}")
.asString();
require 'uri'
require 'net/http'

url = URI("https://api.leanmcp.com/api/chat-messages/chat/id/{chatId}")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n \"role\": \"user\",\n \"content\": \"Hello, can you help me with my project?\",\n \"metadata\": {\n \"model\": \"claude-3-sonnet\",\n \"tokens\": 150\n },\n \"fileIds\": [\n \"f1a83d84-7154-464c-bd19-a9f10e0a067f\",\n \"f2b94e95-8265-575d-ce2a-b0f21f1b178g\"\n ]\n}"

response = http.request(request)
puts response.read_body
{
  "id": "<string>",
  "chatId": "c1a83d84-7154-464c-bd19-a9f10e0a067f",
  "userId": "<string>",
  "content": "<string>",
  "messageIndex": 1,
  "createdAt": "<string>",
  "updatedAt": "<string>",
  "metadata": {}
}

Authorizations

Authorization
string
header
required

Enter your LeanMCP API key

Path Parameters

chatId
string
required

Chat ID

Example:

"c1a83d84-7154-464c-bd19-a9f10e0a067f"

Body

application/json
role
enum<string>
required

Role of the message sender

Available options:
system,
assistant,
user
Example:

"user"

content
string
required

Content of the message

Example:

"Hello, can you help me with my project?"

metadata
object

Optional metadata as key-value pairs

Example:
{ "model": "claude-3-sonnet", "tokens": 150 }
fileIds
string[]

Array of file IDs to associate with this message

Example:
[
"f1a83d84-7154-464c-bd19-a9f10e0a067f",
"f2b94e95-8265-575d-ce2a-b0f21f1b178g"
]

Response

Message added to chat successfully

id
string
required

Unique message identifier (UUID)

chatId
string
required

Chat ID this message belongs to (UUID)

Example:

"c1a83d84-7154-464c-bd19-a9f10e0a067f"

userId
string
required

User ID who owns this message

role
enum<string>
required

Role of the message sender

Available options:
system,
assistant,
user
content
string
required

Message content/text

messageIndex
number
required

Order of message in the chat (0-based)

Required range: x >= 0
createdAt
string
required

Timestamp when message was created

updatedAt
string
required

Timestamp when message was last updated

metadata
object

Additional metadata for the message