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Letta vs Modal

Letta scores higher on the AgentReady, 72/100 against 55/100. They differ on 11 of the 41 signals. Which ones decides whether an agent can adopt them without a person watching.

What each one is

Letta. Letta is an AI research lab in San Francisco building machines that learn.

Modal. Modal provides a serverless cloud for engineers and researchers who want to build compute-intensive applications without thinking about infrastructure.

Where Letta is ahead

Letta passes clear canonical domain and mcp discoverable, and Modal does not. That is discover, whether an agent can find the product at all without being told it exists.

It also holds understand: authentication documented and limits / constraints documented. Modal misses those.

And on adopt, fast time to first request, copyable quickstart and mcp integration available. Modal misses those.

Finally, on operate, structured, predictable output and agent compatibility verified. Modal misses those.

Where Modal is ahead

Modal passes structured api reference, and Letta does not. That is understand, whether an agent can read the docs and work out how the API behaves before calling it.

It also holds adopt: no mandatory sales call. Letta misses it.

What neither does

Both fail openapi / spec quality, request examples provided, response examples provided, errors and status codes documented, programmatic credential creation, machine-readable errors, retry behavior documented, idempotency support, rate-limit behavior predictable. If your agent needs any of those, you will be building it yourself either way.

Score, pillar by pillar

The AgentReady splits into four pillars, scored separately, because a product can be easy to find and still impossible to adopt.

Discover. Letta leads 100 to 80. Letta misses nothing; Modal misses clear canonical domain, mcp discoverable.

Understand. Both sit at 38/100 here. Letta misses structured api reference, openapi / spec quality, request examples provided, response examples provided, errors and status codes documented; Modal misses openapi / spec quality, authentication documented, request examples provided, response examples provided, errors and status codes documented, limits / constraints documented.

Adopt. Letta leads 81 to 65. Letta misses no mandatory sales call, programmatic credential creation; Modal misses programmatic credential creation, fast time to first request, copyable quickstart, mcp integration available.

Operate is whether an agent can run against it in production and recover when a call fails. Letta leads 67 to 35. Letta misses machine-readable errors, retry behavior documented, idempotency support, rate-limit behavior predictable; Modal misses structured, predictable output, machine-readable errors, retry behavior documented, idempotency support, rate-limit behavior predictable, agent compatibility verified.

Pricing

Letta starts at $0/mo and has a free tier. Modal starts at $0/mo and has a free tier.

Signal by signal

Which to pick

Letta clears more of the signals an agent needs, so it is the safer default for unattended use. Full profiles: Letta and Modal. Alternatives to each: Letta, Modal.

An agent can fetch this as data: POST /v1/compare {"slugs": ["letta", "modal"]}