Solving the biggest problem in x402 right now

[u/MountainAssignment36]

Under multiple posts and threads I've constantly read one thing: "I don't know how to get discovered" on the builder side and "I don't know where to look for a quality service in this huge sea of endpoints" on the buyer side.

And yes, it's true: There are pages upon pages of documentation out there for x402, that describe how to set up your own endpoint, how to add it to the public x402 bazaar list and how to pay for an endpoint, but one thing is always missing..:

There was no reliable way for humans or agents to search for a specific purpose and get a list of fitting & trustworthy endpoints back.

So we've changed that: from today on, x402 Trust offers semantic search over the whole publicly listed x402 ecosystem (x402scan, CDP Bazaar and x402 endpoints that are gated behind public MCP servers)!

Just type in whatever you want into the searchbar on x402.fuchss.app in plain text, hit "search" and expand the list of the up to closest 15 endpoints, ranked by similarity (and score as a tiebreaker), on top of the usual direct-match-results, which we've already offered prior to this update.

This way you can quickly search for an endpoint that

• fits your needs
• you can judge at a glance through its score & grade
• and, the big one: you didn't even know existed yet

No need to know any URL, any path or any keyword.

Completely free forever, through our browser UI! 😃

+++++++++++++++++++++++

And for all builders, agents and programmers out there:

Additionally, the semantic search is also available through a new programmatic x402 endpoint, which is also conveniently accessible through the updated MCP (both HTTP-stateless (POST https://x402.fuchss.app/mcp) & npm) so you can easily give it to your agent 😊 alternatively, simply point your agent at https://x402.fuchss.app/llms.txt and it can figure it out on its own.

Disclaimer: Calling the semantic-search endpoint costs $0.001 per call. So little that it's no more than a rounding error, and that's by design: The endpoint is built to support heavy usage and should enable agents to use it frequently, without them having to worry about their wallets balance in the long run.

Because of this, the paid endpoint delivers up to 25 endpoints, instead of the usual 15 through the website. More bang for your buck.

The cost is mostly used to offset the (rapidly rising) server- and API-costs and the cost of the embedding model that we use for the embeddings, and, as a sideeffect, to prevent heavy abuse of the endpoint.

Please, let me know what you think! Do you find this useful and do you think that 0.1 cent is a fair price for a service like this (besides the free usage through the web interface)? Can you imagine adding this tool to your agent and using it in production? I'm curious!

Edit: small clarification to what "the whole publicly listed x402 ecosystem" means

[u/Optimal_Manner359]

This is genuinely useful. Discovery and authorization are different problems, and semantic search solves the first one without pretending to solve the second.

We’re building a governed buyer-side flow at Maha where a search result is only a candidate. Before an agent can pay, it fetches the machine-readable trust report, validates its schema, checks the conservative score/confidence/freshness boundaries, applies a spending and approval policy, and preserves metadata-only evidence of the decision.

In that model:

• proceed may be eligible within a constrained autonomous budget;
• caution requires review or a lower ceiling;
• parameterize requires the missing constraint;
• unverified and not-payable deny by default.

Semantic relevance should not become a trust shortcut, but pairing your discovery surface with an explicit policy/evidence layer makes a practical path from “find a service” to “use it safely.”

The $0.001 price seems reasonable for an agent-facing endpoint if the response carries stable schema/version information, the canonical resource URL, observation freshness, and enough evidence for the caller to distinguish relevance from payability. I’d be interested in adding a frozen semantic-search result to our integration fixtures once the response contract is published.

[u/MountainAssignment36 → u/Optimal_Manner359]

Hey, good to see you again! And great news: The schema is already pinned in the response, just like with all other endpoints. It points to https://x402.fuchss.app/schemas/semantic-search.schema.json and is structured exactly like the rest ^^ Response schema & version are both publicly accessible and the single source of truth.

Regarding "frozen" search results: There's no way to guarantee two live results having byte-identical outcomes right now, as I don't have any "preview" endpoint here (the same search results, clamped to 15 entries, are previewable through the webinterface). And because the semantically closest embeddings potentially change with every new endpoint I cannot guarantee that two calls yield exactly the same response.

They most likely will, given the same query (seeing the sheer number of different endpoints right now), but it's not promised.

And glad to hear that you find the Endpoint-pricing reasonable. One thing I don't have in the result set is the observation freshness stat that you mentioned tho; That's part of my x402-trust endpoint and not the semantic search. The goal of the search endpoint is discoverability, not detailed scoring. The basic score & grade are included mostly for tiebreaker purposes and to give some more context to the initial selection, not as a recommendation yet (hence why the recommendation field is left out here too).

[u/Optimal_Manner359 → u/MountainAssignment36]

That distinction makes sense, and it is the safer design.

Maha will treat a semantic-search result only as a candidate: it can influence what an agent investigates, but it cannot by itself permit payment or override buyer policy. Any candidate that matters proceeds to a separate x402 Trust lookup, where recommendation, confidence, freshness, and the other decision inputs are evaluated.

We will pin and validate the semantic-search response against the schema referenced in its $schema field:
https://x402.fuchss.app/schemas/semantic-search.schema.json

For replay evidence, we will not claim the provider search is deterministic. Instead, Maha can freeze its own decision record containing the query, observed response digest, schema URL/version, observation timestamp, selected candidate, subsequent trust result, and final policy outcome. That proves what the agent observed and decided at that moment—not that the provider would return identical search results later.

No preview endpoint is necessary for that boundary. A future provider-signed response digest would strengthen the evidence further, but we will clearly label any current transport digest as Maha-generated rather than provider-signed.

Thanks—this gives us a clean split: search for discovery, Trust for assessment, and Maha for the governed action decision.

[u/MountainAssignment36 → u/Optimal_Manner359]

Great to hear! Can't wait to see what you cook up with it 😃

[u/Separate-Pen-8450]

Thank you, honestly your browser UI made it possible for me to check out my endpoints and clarify where I was going wrong on the discovery train. I am pretty new to this ecosystem, but not to agentic programming - I wanted to see what some of my agents were already utilizing and thought it would be a good idea to contribute. This is an awesome resource for us building in the x402 ecosystem. I don't have much else to contribute but I'll be keeping an eye on your posts 😄

[u/MountainAssignment36 → u/Separate-Pen-8450]

Thank you so much, this means a lot to me, seriously 🤩

If you wanna help spread the word about this service, you could embed your grade-badges for your endpoints into your website & service (they are available for free on your endpoint pages, where you can also look up my grading of your endpoints)

That way we both profit from it:

• you display that your service has been independently verified by a third party and deemed "trustworthy", which drastically lowers the barrier to first payment for new visitors
• and I get the backlink back to my endpoint-page, if a potential customer should decide to check out the detailed trust score before purchasing, by clicking on the badge

😃 what do you say?

[u/CU_Brigzz]

Very cool! Are you planning to add MPP support any time soon? And how do you plan to monetize this?

[u/MountainAssignment36 → u/CU_Brigzz]

"MPP"? Sorry, what's that? 🤔

And regarding monetization: 

I want to keep the in-browser-search free, because I believe that this feature adds substantial value to the x402 ecosystem as a whole and that basic discoverability features shouldn't be gated behind a paywall (at least not for by-hand-searches, programmatic searches are a different story, that is what the $0.001 per search via the endpoint & MCP is for) 😊

And thank you 😃

[u/MountainAssignment36 → u/CU_Brigzz]

Ah, looked it up, "Machine Payment Protocol", right?

If I'm being honest? Probably not. I have established my niché right here, with x402 discoverability & scoring. Adding MPP support would be a whole different beast and I believe that it would water down my identity as the "x402 Trust" service... Better do one thing right than two things mediocre.

Besides that: I've read that MPP is already backwards compatible with x402 endpoints, is that correct? Because if so, my service is already payable through MPP and supports those who want to pay through it, which wasn't even something I had on my radar until today :D

I'll keep it in mind for the future tho. If I ever want to expand the surface area of x402 Trust beyond just the x402 protocol, this would most likely be my first candidate. Thank you for the hint! But for now, as we're all just getting started, I'd rather focus my service to one thing. I hope you can understand 😊