𝗠𝗖𝗣 𝗦𝗘𝗣 𝟮𝟭𝟬𝟲: 𝗕𝗘𝗧𝗧𝗘𝗥 𝗧𝗢𝗢𝗟 𝗩𝗔𝗟𝗜𝗗𝗔𝗧𝗜𝗢𝗡

𝗠𝗖𝗣 𝗦𝗘𝗣-𝟮𝟭𝟬𝟲: 𝗕𝗘𝗧𝗧𝗘𝗥 𝗧𝗢𝗢𝗟 𝗩𝗔𝗟𝗜𝗗𝗔𝗧𝗜𝗢𝗡

MCP updated its protocol. SEP-2106 is now live. This change improves how tools describe inputs and outputs.

Previously, you had few options. You used a small set of JSON Schema rules. Complex logic lived in a description paragraph.

The system failed to check those rules. The LLM had to guess. If the LLM failed, the tool errored out.

Now, you use the full JSON Schema 2020-12 set. You put rules in the schema.

Benefits for you:

• Conditionals: If field A is true, field B is required.
• Options: Pick one of three choices.
• References: Reuse the same address format in multiple places.

The runtime catches bad calls early. It rejects them before they reach your tool.

Other updates:

• Output shapes are flexible. You return arrays or single values.
• Structured content uses a plain unknown type.

Note: old clients struggle with non-object results. Use a text fallback during the shift.

Source: https://dev.to/pueding/mcp-sep-2106-full-json-schema-2020-12-in-tool-io-ee7 Optional learning community: https://t.me/GyaanSetuAi