Choose a model

Model Use it for Context Serving profile
Fantail Completions, quick fixes, review comments, test scaffolds, and short agent loops. 32K Latency-first, low-cost coding assistance.
Moa Large refactors, architecture work, security reviews, and multi-file planning. 200K Reasoning-first execution for complex software engineering tasks.

Use a model

Pass the model identifier where you start the run. The identifiers are fantail and moa.

Fantail

Fantail is built for interactive coding where feedback speed matters. It is the best default for small, local edits and repeated assistant loops.

  • Best for autocomplete, quick bug fixes, code review notes, documentation snippets, and small tests.
  • Works well when the relevant files are already in the prompt or easy for the agent to inspect.
  • Use Moa instead when the task depends on broad architecture or a large amount of repository context.

Read the Fantail technical report.

Moa

Moa is built for deeper software engineering work. It has a larger context window and is a better fit when the model needs to reason across many files or constraints.

  • Best for large refactors, migration plans, security audits, technical design, and repository analysis.
  • Use it when the model needs to compare patterns across a codebase before making changes.
  • Switch back to Fantail for final polish, small follow-up edits, and fast review cycles.

Read the Moa technical report.

Common patterns

  • Start fast. Use Fantail for the first pass when the task is scoped to a file, function, or failing test.
  • Escalate for context. Switch to Moa when the answer depends on architecture, cross-package contracts, or hidden coupling.
  • Keep the model explicit. Include the model in scripts and SDK calls so runs are repeatable.