fettle-mcp

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Update a heartbeat monitor

update_heartbeat

Idempotent

Modify a heartbeat's name, timing, channels, or tags without resetting its current deadline; only supplied fields change. Use pause/resume to stop or restart late alerts.

Instructions

Change one heartbeat's name, timing, channels or tags; only the fields you pass change. A new period or grace applies from the next ping: the current deadline (overdue_at) is not recomputed. To stop or restart late alerts use pause_heartbeat or resume_heartbeat instead; ping_url never changes. Requires a key with the write scope. An invalid argument is a 422 naming it; never send null. Returns the heartbeat. Example: {"heartbeat_id": "", "grace_seconds": 7200}

Input Schema

TableJSON Schema

Name	Required	Description
`name`	No	Display name, 1 to 255 characters.
`tags`	No	Replaces the whole tag list when passed, at most 10; [] clears it; omit it to keep the tags. Each tag is trimmed, lowercased and deduplicated on write, at most 50 characters of a-z, 0-9 and : _ . / -, starting with a letter or digit. Reuse names from list_tags rather than inventing near-duplicates.
`channel_ids`	No	Notification channel uuids from list_channels. When passed it replaces the whole binding; [] clears it, after which every verified, active channel is alerted; omit it to keep the binding. An id that is not an active channel of this organization is a 404.
`heartbeat_id`	Yes	The heartbeat's uuid from list_heartbeats. An id that is not a heartbeat of this organization, or a deleted one, is a 404.
`grace_seconds`	No	Extra seconds of silence tolerated after the period before the heartbeat is reported late, 0 to 2592000; it may exceed the period.
`period_seconds`	No	How often the job runs, 60 to 2592000 seconds. To ping every N seconds and be alerted after T seconds of silence, set period_seconds = N and grace_seconds = T - N (T at least N).
`notification_cooldown_seconds`	No	60 to 86400 seconds; 1800 when not set on create. Only holds back a duplicate first alert for the same incident within that window. Repeat reminders while an incident stays open and unacknowledged follow the plan's renotify_interval_seconds and renotify_max_count (get_plan_usage; 0 means no reminders) instead, and the recovery alert is never held back.

Output Schema

TableJSON Schema

Name	Required	Description
`id`	Yes
`name`	Yes
`tags`	No
`state`	Yes	Known values: PENDING, UP, DOWN, PAUSED.
`ping_url`	Yes
`is_active`	Yes
`created_at`	Yes
`overdue_at`	Yes
`updated_at`	Yes
`channel_ids`	No
`last_ping_at`	Yes
`grace_seconds`	Yes
`last_start_at`	Yes
`period_seconds`	Yes
`last_success_at`	Yes
`last_duration_ms`	Yes
`notification_cooldown_seconds`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed8 schema fields changedv0.6.1Oct 20, 2026

addedInput schema / properties / channel_ids / description

Added value: +"Notification channel uuids from list_channels. When passed it replaces the whole binding; [] clears it, after which every verified, active channel is alerted; omit it to keep the binding. An id that is not an active channel of this organization is a 404."

addedInput schema / properties / grace_seconds / description

Added value: +"Extra seconds of silence tolerated after the period before the heartbeat is reported late, 0 to 2592000; it may exceed the period."

addedInput schema / properties / heartbeat_id / description

Added value: +"The heartbeat's uuid from list_heartbeats. An id that is not a heartbeat of this organization, or a deleted one, is a 404."

addedInput schema / properties / name / description

Added value: +"Display name, 1 to 255 characters."

addedInput schema / properties / notification_cooldown_seconds / description

Added value: +"60 to 86400 seconds; 1800 when not set on create. Only holds back a duplicate first alert for the same incident within that window. Repeat reminders while an incident stays open and unacknowledged follow the plan's renotify_interval_seconds and renotify_max_count (get_plan_usage; 0 means no reminders) instead, and the recovery alert is never held back."

addedInput schema / properties / period_seconds / description

Added value: +"How often the job runs, 60 to 2592000 seconds. To ping every N seconds and be alerted after T seconds of silence, set period_seconds = N and grace_seconds = T - N (T at least N)."

addedInput schema / properties / tags / description

Added value: +"Replaces the whole tag list when passed, at most 10; [] clears it; omit it to keep the tags. Each tag is trimmed, lowercased and deduplicated on write, at most 50 characters of a-z, 0-9 and : _ . / -, starting with a letter or digit. Reuse names from list_tags rather than inventing near-duplicates."

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "channel_ids": {
+      "items": {
+        "format": "uuid",
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "created_at": {
+      "type": "string"
+    },
+    "grace_seconds": {
+      "type": "integer"
+    },
+    "id": {
+      "format": "uuid",
+      "type": "string"
+    },
+    "is_active": {
+      "type": "boolean"
+    },
+    "last_duration_ms": {
+      "anyOf": [
+        {
+          "type": "integer"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "last_ping_at": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "last_start_at": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "last_success_at": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "name": {
+      "type": "string"
+    },
+    "notification_cooldown_seconds": {
+      "type": "integer"
+    },
+    "overdue_at": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "period_seconds": {
+      "type": "integer"
+    },
+    "ping_url": {
+      "type": "string"
+    },
+    "state": {
+      "description": "Known values: PENDING, UP, DOWN, PAUSED.",
+      "type": "string"
+    },
+    "tags": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "updated_at": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "id",
+    "name",
+    "state",
+    "period_seconds",
+    "grace_seconds",
+    "ping_url",
+    "last_ping_at",
+    "last_success_at",
+    "last_start_at",
+    "last_duration_ms",
+    "overdue_at",
+    "notification_cooldown_seconds",
+    "is_active",
+    "created_at",
+    "updated_at"
+  ],
+  "type": "object"
+}

First observedv0.5.4Oct 20, 2026

TDQS

A4.9/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Goes well beyond the annotations (which only declare non-read-only, idempotent, non-destructive). It discloses the delayed effect of period/grace ('applies from the next ping: the current deadline (overdue_at) is not recomputed'), the required write scope, the 422-on-invalid-argument contract with the offending field named, and the null prohibition.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core operation and update semantics, then progressively narrower detail (timing caveat, sibling routing, auth, error contract, example). Every sentence carries distinct operational information with no filler or restatement of the name.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Covers everything an agent needs: what changes and what does not, side-effect timing, sibling routing, permission requirements, error shape, and a call example. Return values are handled by the existing output schema, so their omission is correct.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, but the description adds cross-parameter semantics the schema does not state at the tool level: partial-update behavior, the timing interaction (new period/grace only takes effect from the next ping), and a concrete example pairing heartbeat_id with grace_seconds.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (Change) and resource (one heartbeat) with the exact field set it touches (name, timing, channels, tags). It also differentiates from adjacent siblings by naming pause_heartbeat and resume_heartbeat as the tools for a different intent, so an agent can route without opening schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicit when-to-use and when-not-to-use: 'only the fields you pass change' defines the partial-update contract, and 'To stop or restart late alerts use pause_heartbeat or resume_heartbeat instead' names the alternatives and the condition that selects them. It further warns that ping_url never changes, removing a plausible mis-selection.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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