ARCHIVED TRAINING / modelcontextprotocol/python-sdk

modelcontextprotocol__python-sdk-1864

This is a preserved training example. Membership in the current training wave has not been verified.

Problem statement

URL Parameters Not Decoded in Dynamic Resources
### Initial Checks

- [ ] I confirm that I'm using the latest version of MCP Python SDK
- [x] I confirm that I searched for my issue in https://github.com/modelcontextprotocol/python-sdk/issues before opening this issue

### Description

Dynamic URL resource parameters in MCP protocol are not automatically URL-decoded, causing encoded characters (like %20 for spaces and %C3%A9 for accented characters) to be passed as-is to resource handlers instead of their decoded equivalents.


Here is a simple log for the bug: 
- **before**
```
2025-06-17 14:43:44,385 [INFO] kn-graph: Found 0 products matching 'stick%20correcteur%20teint%C3%A9%20anti-imperfections%20rechargeable%20au%20zinc' - (logger.py:226)
```

- **after explicit decode**
```
2025-06-17 14:55:10,173 [INFO] kn-graph: Found 10 products matching 'stick correcteur teinté anti-imperfections rechargeable au zinc' - (logger.py:226)
```

### Example Code

```Python
@mcp.resource("products://search/{product_identifier}")
    def find_similar_products(product_identifier: str):
        """
        Find similar products based on a given product identifier.
        :param product_identifier: The identifier of the product (product name or code).
        :return: Similar products or an error message if none are found.
        """
        print(product_identifier)
        """
         -- walkaround: explicit decoding
        from urllib.parse import unquote
        print(unquote(product_identifier))
        """
```

### Python & MCP Python SDK

```Text
# uv pip list | grep "mcp"
mcp                          1.9.2
# python --version
Python 3.13.4
```

Training membership

opd_e4b_cispo_v5 opd_e4b_hybrid_v3 opd_e4b_onpolicy_v3 opd_e4b_pure_v6b opd_e4b_pure_v7 opd_e4b_pure_v7b rft_e4b_aligned_v2 rft_v1 rft_v2

Task issues extracted from preserved verified_rft_messages training examples. This is not a verified current RL wave manifest.

Task and snapshot provenance

Snapshot captured 2026-11-12T17:06:59.476467+00:00 · Autoresearch-Arena/gemma-4-developer-agent

{
  "datasets": [
    "opd_e4b_cispo_v5",
    "opd_e4b_hybrid_v3",
    "opd_e4b_onpolicy_v3",
    "opd_e4b_pure_v6b",
    "opd_e4b_pure_v7",
    "opd_e4b_pure_v7b",
    "rft_e4b_aligned_v2",
    "rft_v1",
    "rft_v2"
  ],
  "examples": 32,
  "instance_id": "modelcontextprotocol__python-sdk-1864",
  "problem_statement": "URL Parameters Not Decoded in Dynamic Resources\n### Initial Checks\n\n- [ ] I confirm that I'm using the latest version of MCP Python SDK\n- [x] I confirm that I searched for my issue in https://github.com/modelcontextprotocol/python-sdk/issues before opening this issue\n\n### Description\n\nDynamic URL resource parameters in MCP protocol are not automatically URL-decoded, causing encoded characters (like %20 for spaces and %C3%A9 for accented characters) to be passed as-is to resource handlers instead of their decoded equivalents.\n\n\nHere is a simple log for the bug: \n- **before**\n```\n2025-06-17 14:43:44,385 [INFO] kn-graph: Found 0 products matching 'stick%20correcteur%20teint%C3%A9%20anti-imperfections%20rechargeable%20au%20zinc' - (logger.py:226)\n```\n\n- **after explicit decode**\n```\n2025-06-17 14:55:10,173 [INFO] kn-graph: Found 10 products matching 'stick correcteur teinté anti-imperfections rechargeable au zinc' - (logger.py:226)\n```\n\n### Example Code\n\n```Python\n@mcp.resource(\"products://search/{product_identifier}\")\n    def find_similar_products(product_identifier: str):\n        \"\"\"\n        Find similar products based on a given product identifier.\n        :param product_identifier: The identifier of the product (product name or code).\n        :return: Similar products or an error message if none are found.\n        \"\"\"\n        print(product_identifier)\n        \"\"\"\n         -- walkaround: explicit decoding\n        from urllib.parse import unquote\n        print(unquote(product_identifier))\n        \"\"\"\n```\n\n### Python & MCP Python SDK\n\n```Text\n# uv pip list | grep \"mcp\"\nmcp                          1.9.2\n# python --version\nPython 3.13.4\n```",
  "repo": "modelcontextprotocol/python-sdk",
  "source": "v2/experiments/train_data/opd_e4b_cispo_v5/verified_rft_messages.jsonl",
  "source_sha256": "a43610ad0dfb6ace95375cfae09000f41afc0338cc925af870a4ade7a9b20c4c"
}

{
  "captured_at": "2026-11-12T17:06:59.476467+00:00",
  "membership": "archived training",
  "membership_evidence": "Task issues extracted from preserved verified_rft_messages training examples. This is not a verified current RL wave manifest.",
  "name": "Preserved post-training task archive",
  "source": "Autoresearch-Arena/gemma-4-developer-agent",
  "source_revision": "016496de222aaafca0d4ee4c18efc63ba616f76e",
  "sources": [
    {
      "path": "v2/experiments/train_data/opd_e4b_cispo_v5/verified_rft_messages.jsonl",
      "sha256": "a43610ad0dfb6ace95375cfae09000f41afc0338cc925af870a4ade7a9b20c4c"
    },
    {
      "path": "v2/experiments/train_data/opd_e4b_hybrid_v3/verified_rft_messages.jsonl",
      "sha256": "bd326303eb127e8e5e08f03daf97bb88d79d19709d59f3f93f348bc56686a8df"
    },
    {
      "path": "v2/experiments/train_data/opd_e4b_onpolicy_v3/verified_rft_messages.jsonl",
      "sha256": "960c680e797e823a0d3a22f4b1d5ef60a72971373d703b877340b0c9126aaf68"
    },
    {
      "path": "v2/experiments/train_data/opd_e4b_pure_v6a/verified_rft_messages.jsonl",
      "sha256": "f045b7ca5b3883a1e2eaee81e1c02a4a1b53dd7b7b36e98bacb2ba5823a15148"
    },
    {
      "path": "v2/experiments/train_data/opd_e4b_pure_v6b/verified_rft_messages.jsonl",
      "sha256": "0f62460a9706eea5e1605255896f191ab00cb5706c5f1f2e1c293e9a718218dc"
    },
    {
      "path": "v2/experiments/train_data/opd_e4b_pure_v7/verified_rft_messages.jsonl",
      "sha256": "e37f7bd675322f3f81500b73559d60d5f602ca0537bf19f5cb06332c728c7b72"
    },
    {
      "path": "v2/experiments/train_data/opd_e4b_pure_v7b/verified_rft_messages.jsonl",
      "sha256": "b864bdc8695183433eef6e31cb8d33fad44ba3aded2170c1ade4ad5b2944ce23"
    },
    {
      "path": "v2/experiments/train_data/opd_e4b_self_audit_v4/verified_rft_messages.jsonl",
      "sha256": "0026023745afb8f3dc1c176dc7f7171157b4ad5a66656b524af218e8e19ceee6"
    },
    {
      "path": "v2/experiments/train_data/rft_e4b_aligned_v2/verified_rft_messages.jsonl",
      "sha256": "92a4515fee9d152b0d4c510ee3ce4caaaffe2003ba7584469f8027f174aab18c"
    },
    {
      "path": "v2/experiments/train_data/rft_v1/verified_rft_messages.jsonl",
      "sha256": "a42453ccd7ac7680b0a03865e8e7080bc8bf74c8d9d193b440c441ed46f8512b"
    },
    {
      "path": "v2/experiments/train_data/rft_v2/verified_rft_messages.jsonl",
      "sha256": "18f4b3bd7e651f83c6acab479c9475e3fa50dc652a384f309e97146983ac85ba"
    }
  ]
}