For general information on how the Python agent API calls relate to each other, see the API guide.

newrelic.agent.add_custom_parameter(key, value)
Adds a custom attribute to a transaction.


This call records a custom attribute (a key/value pair attached to your transaction). (The call name is add_custom_parameter because "custom attributes" were previously called "custom parameters.")

Attributes may be found in APM if the transaction is associated with an error or if a transaction trace is generated for that transaction. Attributes can also be found and queried in New Relic One.

Before you create custom attributes, review our list of reserved terms used by NRQL.


Parameter Description



Required. The key name. Only the first 255 characters are retained.


string, integer, float, boolean

Required. The string value to add to the current transaction. Only the first 255 characters are retained.

Return value(s)

Returns True if attribute was added successfully. 


Adding custom parameters to background task

An example of adding custom parameters to a background task:

def send_request(): 
	response ='http://URL_path', headers=headers, data=data) 
	newrelic.agent.add_custom_parameter('url_path_status_code', response.status_code) 

Using custom parameters to troubleshoot

You can also use custom parameters to troubleshoot performance issues. For example, you might see occasional slow response times from a pool of memcache instances, but you don't know what instance is causing the problem. You might add an attribute to the transaction indicating the server, like so:

# Set server_ip to be the current server processing the transaction

newrelic.agent.add_custom_parameter("memcache_query_frontend_lookup", server_ip)

For more help

If you need more help, check out these support and learning resources: