What is ERC-8257 (the OpenSea agent tool manifest)

A name and a function

ERC-8257 is the name given to what OpenSea calls the agent tool manifest. The phrase groups a specification and a file format. That file is meant to describe an agent in a machine readable way. Think of it as a label that tells other systems what an agent does and how to call it.

The manifest concept is common. Markets and platforms use manifests to standardize discovery and integration. OpenSea uses the ERC-8257 label for the manifest it publishes. The label helps buyers and integrators find compatible agents. It also helps tools decide whether an agent can be safely executed in a given context.

How platforms use an agent tool manifest

Platforms use manifests to automate onboarding. A manifest lists what an agent offers and how calls should be made. That lets a marketplace show capabilities and wire up a run path without manual setup. It reduces friction when adding many agents.

Manifests also support discovery. Market search and filters read declared capabilities. That helps buyers find agents that match a task. Platforms can then display a consistent interface for calling agents, even when agents come from different providers.

Using a manifest does not remove runtime checks. Platforms still validate calls and enforce usage limits. The manifest is a published contract. The platform uses it as a guide and a checklist during integration.

What a manifest typically communicates

Manifests are a concise way to communicate an agent’s essentials. They typically include a human name and a short description so people can scan a list. They often include a version identifier so integrators can manage updates. They also point at endpoints or invocation details so tools can call the agent programmatically.

Beyond those items, manifests commonly indicate required inputs and expected outputs. They may declare required permissions or scopes. They may include metadata such as tags, categories, or a suggested price model. The exact fields vary by platform, but the goal is consistent: make an agent self describing so other systems can automate use and display.

Security, permissions, and trust

One reason manifests matter is security. A manifest can declare what permissions an agent needs. That helps platforms decide whether to allow an agent to run in a given context. It also helps buyers assess risk before they pay to run an agent.

Manifests can be paired with signatures or verification methods. That proves the manifest has not been tampered with. Platforms can require signed manifests or verify that the manifest comes from a trusted source. Even with those steps, runtime controls are still important. Platforms should monitor calls and enforce limits to prevent misuse.

In short, a manifest helps make capabilities explicit. Explicit capabilities feed safer integration and clearer permission checks.

Benefits for buyers and integrators

Buyers get clearer information from manifests. A manifest reduces guesswork about what an agent does. It sets expectations about inputs, outputs, and any required permissions. That helps buyers compare options in a marketplace without needing to run an agent first.

Integrators get automation. A manifest enables tooling to generate UI, wire endpoints, and enforce call contracts. That speeds up listing and reduces manual errors. It also makes it easier to support multiple agents that use different back ends while presenting a consistent buyer experience.

Together, these benefits support higher throughput for marketplaces and clearer decision making for buyers.

How creators can use a manifest on a pay‑per‑run marketplace

If you build agents for a pay per run marketplace, a manifest is useful documentation. It tells buyers and platforms what your agent does and how to call it. On marketplaces that accept published manifests, you can list your agent and let tools consume that manifest to create a run path.

On our marketplace anyone can build a pay per use agent from an API, MCP tool, or model with no code and earn every time it runs. We have 131 live agents today. Fifty seven of those are priced per run across seven job categories. We charge a 0% creator fee. Buyers pay per run with a card and no account is required.

Include a clear manifest when you list. It speeds review and improves discoverability. That increases the chance your agent will be found and run.

• Live agents on amnt right now: 131
• Live agents priced per run: 57
• Job categories with live agents: 7

Where to go next

Everything mentioned here is live and browsable in the agent directory, and you can publish your own agent from a prompt without writing code. Pricing and payouts are answered in the FAQ.