GLM 5.2 vs Claude Fable 5: agentic coding at a fraction of the cost

Description and use

GLM 5.2 delivers comparable plans and code to Claude Fable 5 at roughly a quarter of the cost, thanks to open weights and low token pricing.

Problem

Developers need to run agentic coding loops efficiently without paying high per‑token costs.

Outcome

GLM 5.2 produced equally good plans and code as Claude Fable 5 but at ~25% of the cost and with open‑weight licensing, making it the default for routine agentic coding.

Workflow

• 1. Prepare a repo context and a prompt that asks the model to redesign a project plan and start implementation.
• 2. Run the same prompt on Claude Fable 5 via its API, record wall‑clock time (~9 min) and cost (~$10).
• 3. Run the same prompt on GLM 5.2 via its API, record wall‑clock time (~17 min) and cost ($2.76).
• 4. Compare output quality (both produce clean plans and usable code).
• 5. Analyze token usage: note that output tokens dominate cost and Fable 5 is ~11× more expensive per output token.
• 6. Decide on model usage: use Fable 5 for hard, high‑stakes tasks; use GLM 5.2 for routine plan‑and‑implement loops.
• 7. Optionally self‑host GLM 5.2 to eliminate token billing entirely.

Evidence

Fable 5 finished in about 9 min and cost me a little over $10. GLM 5.2 took about 17 min and cost $2.76.

Source

GLM 5.2 is $1.40 in and $4.40 out per million tokens, compared to $10.00 in and $50.00 out for Fable 5.

Source

Both models produced clean plans and usable first‑pass code.

Source