Claude 4.5 Sonnet API: balanced intelligence for production

Anthropic recommends Sonnet 4.5 as the default model when you are unsure which Claude model to use. It is described as offering the best balance of intelligence, speed, and cost for most use cases, with exceptional performance in coding and agentic tasks. For teams, this means the Claude 4.5 Sonnet API is a strong all-around choice for production assistants, technical reasoning, and workflows where both quality and throughput matter. Many teams start with the Claude 4.5 Sonnet API and only switch when a different tradeoff is required.

Yes. Official release notes describe Sonnet 4.5 as the best coding model to date. Improvements span planning and system design, better instruction following, and stronger security engineering. These upgrades make the Claude 4.5 Sonnet API well suited for code review, refactoring, migration plans, and test strategies. It can also explain changes and risks clearly, which helps teams review and ship faster. For long diffs or design reviews, the Claude 4.5 Sonnet API stays consistent and detail oriented.

Sonnet 4.5 is described as the best model for complex agents and coding, with the highest intelligence across most tasks. Release notes also highlight advances in agent capabilities, such as longer autonomous operation, better context awareness, and enhanced tool usage. In practice, the Claude 4.5 Sonnet API can sustain multi-step workflows, track progress, and coordinate tools more effectively. It is a reliable base model for agentic systems and operational automation, especially when tasks require planning and verification.

Yes. Official model documentation lists a 200K context window and a 1M beta context option for Sonnet 4.5. This lets the Claude 4.5 Sonnet API ingest long briefs, large policy stacks, or multi-file research notes in a single request and return summaries that stay grounded in the original materials. For teams working with large inputs, long context reduces heavy chunking and preserves coherence across sections. Claude 4.5 Sonnet API is a natural fit for long-form analysis and synthesis.

Use the EvoLink endpoint https://api.evolink.ai/v1/messages. Send Authorization: Bearer YOUR_API_KEY and Content-Type: application/json, then set model to claude-sonnet-4-5-20250929 with a required max_tokens value and a messages array. EvoLink returns the next assistant response and supports single queries or multi-turn conversations with prior turns. This is the standard integration path for the Claude 4.5 Sonnet API on EvoLink, and you can reuse it across apps and models.

Use the exact model ID claude-sonnet-4-5-20250929 in the model field. EvoLink lists the available Claude IDs, including claude-haiku-4-5-20251001, claude-opus-4-1-20250805, claude-sonnet-4-20250514, and claude-opus-4-5-20251101. Using the published ID ensures your Claude 4.5 Sonnet API requests route to the intended model and remain compatible with EvoLink’s documented schema. You can swap IDs to compare models while keeping the same request shape for the Claude 4.5 Sonnet API.

EvoLink accepts text and image content in Claude requests, so the Claude 4.5 Sonnet API can handle multimodal prompts. The API supports max_tokens (required, x >= 1), temperature and top_p in the 0.0 to 1.0 range, top_k with x >= 0, stop_sequences, and stream for server-sent events. You can also include system, thinking, metadata, service_tier, context_management, and mcp_servers for additional control and context management. These settings help the Claude 4.5 Sonnet API balance stability, creativity, and latency.

You can define tools in the tools array and control their usage with tool_choice. EvoLink supports tool_choice options of auto, any, tool, and none, and lists tool definitions that include custom tools and built-in tool types such as bash, code execution, computer use, memory, text editor, web search, and web fetch. This lets the Claude 4.5 Sonnet API call tools in a controlled way for agent workflows while keeping tool usage explicit. Use tools when your workflow needs retrieval, execution, or UI actions.