Agent access

Browser support

In-browser agent tools use the browser's own WebMCP surface, document.modelContext. Coach Anvil publishes tools only when the browser provides that surface.

• Verified working: Chrome 152 and Chromium 151, started with --enable-experimental-web-platform-features.
• Every other browser: Coach Anvil works exactly as it always has. No tools are published, nothing is degraded, and no extension is installed.
• Tools live for one page. They disappear on reload, on navigation and when you sign out, and they never carry across accounts.
• Each page publishes only the tools that match what you are looking at. A workout page offers workout tools; a plan page does not.

A browser agent shares the page's own writer and its offline queue. It cannot open a second connection behind the page, and a set it queues is not a saved set until the server acknowledges it.

Connecting an agent

In your browser

1. Sign in to Coach Anvil in a supported browser.
2. Open Settings → Agent access.
3. Choose the access you want to grant, confirm you are 18 or older, agree to share the selected fitness data, and select Enable Browser Access.
4. Reload the Coach Anvil page you want the agent to work on.

An external agent

1. In the agent client, add Coach Anvil's MCP server at https://coachanvil.com/api/mcp.
2. The client is sent to Coach Anvil to sign in. Coach Anvil — never the agent — collects your sign-in.
3. Review the connection screen: it names the client, lists exactly which access it asked for, and asks you to confirm you are 18 or older and agree to share the selected fitness data.
4. Approve, and the client receives its own Coach Anvil credential. Connection consent lasts 90 days; after that the client asks again.

An agent never receives your Coach Anvil password or your Google sign-in, and it is never issued a Coach Anvil session cookie. If any agent asks you for a password, a one-time code or a token, that request did not come from Coach Anvil.

What an agent can do directly

These are real requests, in the words you would use. Each maps to a bounded Coach Anvil tool with a fixed schema.

Plan

• “What workout is scheduled for me today?”
• “Show me week 3 of my current plan.”
• “Move Thursday's workout to Saturday.”
• “Start a four-week strength plan, three days a week, 45 minutes a session.”

Log

• “Log 3 sets of 8 at 40 kg for the workout I have open.”
• “Substitute the leg press for goblet squats in this session.”
• “Finish this workout — it took 52 minutes.”

Review

• “How has my back squat progressed over the last eight weeks?”
• “What are my current personal records?”
• “How consistent has my training been this quarter?”

Equipment

• “What equipment is in my home gym inventory?”
• “Add a 24 kg kettlebell to my garage inventory.”

Changes that replace or remove things — swapping two plan days, a bulk prescription edit, archiving or deleting a plan, postponing a deload, taking a workout over from another device, and every plan generation — are held until you confirm them inside Coach Anvil. The agent gets a link, not the change. Repeating a request never records it twice: Coach Anvil replays the original result.

Limitations

• Nothing clinical. Lab results, genetic findings, medical intake, injuries, pain, medication, body composition, and wearable or recovery data have no agent tool at all. Coach Anvil returns a link to the app instead.
• No conversations. Coaching chat, voice history, summaries and plan rationales stay in Coach Anvil.
• No account or billing actions. An agent cannot delete your account, change your subscription, invite anyone, or start a purchase. Those live in Coach Anvil's own settings.
• Your existing limits still apply. Connecting an agent grants no extra capability. Plan tiers, feature availability, usage caps, household roles and guest restrictions are unchanged. Where a capability is not available on an account, the agent is told exactly that and nothing more.
• Only your own data. A request naming someone else's plan, workout or inventory is refused, and the refusal does not reveal whether it exists.
• One writer at a time. If an open Coach Anvil tab holds a workout, an external agent is refused rather than allowed to write over it.
• Read the results, not the labels. Text stored in your data is returned as data. It is never treated as an instruction, and agent-supplied text can never redirect a Coach Anvil link.

Endpoints and discovery

All of these are public metadata locations. None of them returns account data, and none is reachable without a Coach Anvil credential except the discovery documents themselves.

MCP endpoint

https://coachanvil.com/api/mcp

Protected resource

https://coachanvil.com/.well-known/oauth-protected-resource/api/mcp

Authorization server

https://coachanvil.com/.well-known/oauth-authorization-server

Access is requested as named scopes: fitness.read, fitness.write, plans.generate and equipment.write. A client only ever receives the scopes you approved, and only for as long as the connection lasts.

What leaves Coach Anvil

Only the structured fitness fields a tool is defined to return: plan and workout identifiers, exercise names from Coach Anvil's own exercise catalogue, sets, repetitions, durations, loads with their unit, rest, RPE and RIR, adherence counts, personal records, equipment entries, your training preferences and your timezone. Plans and equipment inventories are labelled by number, not by any name you wrote.

Free text you have written — notes, pain reports, coaching messages, plan rationales — is not part of any tool result. Neither is your email address, your billing details or any identifier from a connected health service.

Whatever an agent receives is then held by whoever operates that agent, under their own policy. Coach Anvil cannot reach into an external service to delete a copy it already sent. See the Privacy Policy for retention, and treat connecting an agent as a decision to share that data with it.

Turning it off

1. Sign in and open Settings → Agent access.
2. For an external agent, find the connection and select Unlink. Its credentials stop working immediately, including any it had already issued.
3. For browser tools, select Disable Browser Access. Open pages stop publishing tools.

Unlinking stops all future access and cancels anything still waiting for your confirmation. It does not delete data an agent already received — ask that agent's operator to delete their copy.

Support

Questions about agent access: support@coach.app. Privacy questions: privacy@coach.app.