A WebMCP migration becomes necessary when an existing implementation doesn't behave according to the specification, even if it was built with good intentions. Many websites have received recommendations based on assumptions, unofficial articles, or misinterpretations of the standard, and the result is code that looks correct at first glance but that AI agents can't actually use in practice. Our WebMCP migration and refactoring service starts with a real technical audit and continues with targeted correction of each identified issue, without unnecessarily rebuilding what already works.
When you need a WebMCP migration
There are a few fairly clear signs that a WebMCP implementation isn't functional, even if everything in the source code seems to be in place. If the manifest exists but no agent seems to read it, if the tools are defined as isolated JavaScript functions with no visible connection to the browser, or if the implementation was built based on unofficial guides describing attributes and conventions that don't exist in the specification, it's very likely that the situation requires a migration. You can quickly check the current status using the free WebMCP validator, which shows exactly what is detected and what is missing from a real implementation.
What we check in the audit of the existing implementation
The first step is always a technical audit, carried out manually, not just through an automated tool run. The audit tracks the difference between what appears to exist in the code and what is actually accessible to an AI agent at the moment the page runs.
- The existence and correctness of the WebMCP manifest, including its format and location.
- The presence of attributes or conventions that aren't defined in the official specification.
- How tools are registered, statically in HTML or dynamically through the API.
- The structure of the parameter schemas for each declared tool.
- The actual behavior in the browser, verified through real calls to modelContext.
Why the code looks correct but doesn't register in the browser
One of the most common problems we encounter is an implementation that, read as text, looks perfectly valid: sensible tool names, clear descriptions, seemingly well defined parameters. The problem isn't visible in the editor, it's in the browser's behavior. Many of these implementations use static HTML attributes, hoping that an AI agent will detect them simply by parsing the page. WebMCP doesn't work that way. Tools must be actually registered, at the right moment, through the modelContext API, and if this step is missing, all that remains is decorative markup with no real function for a conversational agent.
Removing invented attributes and conventions
A significant part of the refactoring work consists of removing practices that circulate informally but have no basis in the specification. We've come across custom attributes meant to "mark" an element as an AI tool, data structures assumed to be automatically read by agents, or property names invented by analogy with other technologies. These elements don't produce visible errors, which makes them hard to detect without a dedicated technical review. We identify them, remove them, and replace that logic with the real mechanisms provided by the standard, so the implementation matches exactly what a WebMCP client reads.
Moving from static detection to real registration
The central refactoring in this service is the shift from an approach based on static HTML markup to the programmatic registration of tools through modelContext. This involves correctly defining each tool, with its name, description, and associated parameter schema, and registering it at the right moment in the page's lifecycle. The result is an implementation that can be objectively verified through real calls, not just by reading the source code. For websites with no previous implementation, the process is similar to the one described on the WebMCP implementation page, but here we start from an existing foundation, which we correct instead of building from scratch.
Cleaning up manifests and rebuilding parameter schemas
Incorrect WebMCP manifests are another common cause of failure, either because required fields are missing or because they include information that doesn't match the required format. Similarly, parameter schemas are often written without respecting the expected data types or without the constraints needed for an agent to correctly fill in calls. As part of the migration, we deliver:
- A corrected WebMCP manifest, aligned with the current specification.
- Rebuilt parameter schemas for each tool, with correct types and validations.
- A technical report on the issues initially identified and how they were resolved.
- Final verification of the actual registration of the tools in the browser.
We can't guarantee how a particular external AI agent will interpret or prioritize the exposed tools, since that behavior depends on that system, not on the website's implementation. What we can guarantee is that the implementation matches the specification and is technically verifiable, according to the methodology described on our methodology page.
What the collaboration looks like and how to request a quote
WebMCP migration and refactoring usually takes place in short stages: audit, list of issues, correction, and final verification, so you always know what's changing and why. If your current implementation doesn't seem to work correctly, or you simply want an independent technical confirmation, you can contact us to discuss your specific situation and get an estimate tailored to the complexity of your website.