Call a tool

Executes a tool on the server and returns the MCP CallToolResult directly. Tool-level failures (isError: true in the result) are successful calls — the server answered; only transport/auth errors use the error envelope.

POST /projects/{projectId}/servers/{serverId}/tools/call

Call a tool

cURL

curl --request POST \
  --url https://app.mcpjam.com/api/v1/projects/{projectId}/servers/{serverId}/tools/call \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "toolName": "create_issue",
  "parameters": {
    "title": "Bug: login fails"
  }
}
'

import requests

url = "https://app.mcpjam.com/api/v1/projects/{projectId}/servers/{serverId}/tools/call"

payload = {
    "toolName": "create_issue",
    "parameters": { "title": "Bug: login fails" }
}
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({toolName: 'create_issue', parameters: {title: 'Bug: login fails'}})
};

fetch('https://app.mcpjam.com/api/v1/projects/{projectId}/servers/{serverId}/tools/call', 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://app.mcpjam.com/api/v1/projects/{projectId}/servers/{serverId}/tools/call",
  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([
    'toolName' => 'create_issue',
    'parameters' => [
        'title' => 'Bug: login fails'
    ]
  ]),
  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://app.mcpjam.com/api/v1/projects/{projectId}/servers/{serverId}/tools/call"

	payload := strings.NewReader("{\n  \"toolName\": \"create_issue\",\n  \"parameters\": {\n    \"title\": \"Bug: login fails\"\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://app.mcpjam.com/api/v1/projects/{projectId}/servers/{serverId}/tools/call")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"toolName\": \"create_issue\",\n  \"parameters\": {\n    \"title\": \"Bug: login fails\"\n  }\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://app.mcpjam.com/api/v1/projects/{projectId}/servers/{serverId}/tools/call")

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  \"toolName\": \"create_issue\",\n  \"parameters\": {\n    \"title\": \"Bug: login fails\"\n  }\n}"

response = http.request(request)
puts response.read_body

200

Example

{ "content": [ { "type": "text", "text": "Issue created: #42" } ] }

Authorizations

Authorization · string · header · required

MCPJam API key (sk_…). Create one at Settings → API keys. Guest sessions cannot use the API, and API keys cannot manage other API keys.

Path Parameters

projectId · string · required

ID of the hosted project that contains the server.

serverId · string · required

ID of the server inside the project.

Body

application/json

toolName · string · required

Tool name, exactly as returned by the tools list.

parameters · object

Tool arguments matching the tool's inputSchema. Defaults to {}.

Response

200

application/json

The MCP CallToolResult. Check isError for tool-level failures.

MCP tool execution result, returned verbatim from the server.

content · object[] · required

Content blocks (text, image, resource, ...).

structuredContent · object

Structured output matching the tool's outputSchema, when declared.

isError · boolean

true when the tool reported a failure. The HTTP call still succeeds — the server answered.