Custom API tool sends unset optional header and cookie parameters as empty values or "None"

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Since Nov 10, 2026.

  • #46011 by @TemitopeKadri — open

Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
77/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
python
Domain
api, backend

Research direction

Start in api/core/tools/custom_tool/tool.py at ApiTool.do_http_request and trace how get_parameter_value handles optional query, header, and cookie parameters with missing or null defaults. Check the related custom tool tests and add coverage for omitted optional values and boolean headers. Done means empty and None values are omitted for optional parameters, while a boolean header is sent as lowercase true.

Written by the indexing model from the issue text.

Description

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Dify version

main (b63ed037d0)

Cloud or Self Hosted

Self Hosted (Source)

Steps to reproduce
  1. Create a custom tool (Tools → Custom → Create Custom Tool) from this schema:
openapi: 3.0.0
info: {title: demo, version: "1"}
servers: [{url: https://httpbin.org}]
paths:
  /anything:
    get:
      operationId: listItems
      parameters:
        - {name: X-Request-Id, in: header, required: false, schema: {type: string}}
        - {name: X-Tenant, in: header, required: false, schema: {type: string, default: null}}
        - {name: X-Dry-Run, in: header, required: false, schema: {type: boolean}}
        - {name: session, in: cookie, required: false, schema: {type: string}}
  1. Test the listItems tool with only X-Dry-Run = true filled in (leave the other parameters empty).
✔️ Expected Behavior

Optional header and cookie parameters that have no value are left out, as optional query parameters already are. A boolean header is sent as true, which is how the tool already sends a boolean query parameter (?flag=true).

X-Dry-Run: true
❌ Actual Behavior

Every declared header and cookie is sent, even when it has no value. A default: null is sent as the text None, and a boolean is sent as Python's True:

X-Request-Id:
X-Tenant: None
X-Dry-Run: True
Cookie: session=

APIs that validate these headers then reject the call or treat the value as real, for example a tenant named None or an empty session cookie that replaces the anonymous one.

In ApiTool.do_http_request (api/core/tools/custom_tool/tool.py), query parameters are skipped when get_parameter_value returns "". Header parameters are always set to str(value), and cookie parameters are always set to the raw value. get_parameter_value returns "" for an optional parameter without a default, and returns the schema default (here None) otherwise. A default: null query parameter is affected too: None is not "", so it is sent as ?q=.

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Python
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Merged PRs (30d)
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