MCP Python SDK 2.1.0 · quieter handler errors, leaner content returns — from issue No. 016nofeed.dev
Issue No. 016 · 25 August 2026
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MCP Python SDK 2.1.0 · quieter handler errors, leaner content returns

v2.1.0 (24 Aug): Client takes StdioServerParameters directly. Unexpected tool/resource/prompt exceptions now log once server-side and return only Error executing tool <name> to the client — raise ToolError / ResourceError when the model should see the message.5 Tools annotated to return TextContent / Image / Audio (or lists) no longer advertise outputSchema or fill structuredContent; pass structured_output=True to keep the old shape.5 4 MiB body limit extends to SSE and OAuth. v1.29.1 is the maintenance line with the body-limit and recursive-schema fixes.6

MATTERS TO · anyone shipping MCP servers or clients on the Python SDK
WHAT THE VERDICT MEANS
Available, but early — bugs, limits or price.
Sources for this entry01 OpenAI docs — API pricing (2026-08-25) · 02 OpenAI docs — GPT-5.6 Sol model page (2026-08-25) · 03 HN — GPT 5.6 Sol price reduction (2026-08-25) · 04 OpenAI — GPT-5.6 in Kiro (2026-08-25) · 05 github — MCP Python SDK v2.1.0 (2026-08-25) · 06 github — MCP Python SDK v1.29.1 (2026-08-25)

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