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nks-hub

rybbit-mcp

by nks-hub

User Retention

rybbit_get_retention
Read-onlyIdempotent

Retrieve retention cohort analysis to track how many users return over time, revealing engagement patterns and product stickiness.

Instructions

Get user retention cohort analysis showing how many users return over time periods.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
siteIdYesSite ID (numeric ID or domain identifier)
endDateNoEnd date in ISO format (YYYY-MM-DD)
filtersNoArray of filters. Example: [{parameter:'browser',type:'equals',value:['Chrome']},{parameter:'country',type:'equals',value:['US','DE']}]
timeZoneNoIANA timezone (e.g., Europe/Prague). Default: UTC
startDateNoStart date in ISO format (YYYY-MM-DD)
pastMinutesEndNoAlternative to dates: minutes ago end (default 0 = now)
pastMinutesStartNoAlternative to dates: minutes ago start (e.g., 60 = last hour)

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
dataYesRetention cohorts; periods are percentages per period, null = period not reached yet
modeNo

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed2 schema fields changedv0.8.1
    • changedInput schema / properties / filters / items / properties / parameter / description
      Previous value: -"Filter dimension. One of: browser, browser_version, operating_system, operating_system_version, language, country, region, city, device_type, device_model, app_version, dimensions, referrer, hostname, pathname, page_title, querystring, event_name, channel, utm_source, utm_medium, utm_campaign, utm_term, utm_content, entry_page, exit_page, user_id, lat, lon, timezone, vpn, crawler, datacenter, company, company_type, company_domain, asn_org, asn_type, asn_domain, tag. Custom URL parameters use the prefix 'url_param:NAME' (e.g., 'url_param:campaign_id'). Note: user_id filter checks BOTH the device hash (user_id) and app-provided ID (identified_user_id). device_model and app_version are populated only for app-type sites tracked via SDK."New value: +"Filter dimension. One of: browser, browser_version, operating_system, operating_system_version, language, country, region, city, device_type, device_model, app_version, dimensions, referrer, hostname, pathname, page_title, querystring, event_name, channel, utm_source, utm_medium, utm_campaign, utm_term, utm_content, entry_page, exit_page, user_id, lat, lon, timezone, tag. Custom URL parameters use the prefix 'url_param:NAME' (e.g., 'url_param:campaign_id'). Note: user_id filter checks BOTH the device hash (user_id) and app-provided ID (identified_user_id). device_model and app_version are populated only for mobile-type sites (legacy: app) tracked via SDK."
    • changedOutput schema / (root)
      Previous value: -nullNew value: +{
      +  "$schema": "http://json-schema.org/draft-07/schema#",
      +  "additionalProperties": false,
      +  "properties": {
      +    "data": {
      +      "description": "Retention cohorts; periods are percentages per period, null = period not reached yet",
      +      "items": {
      +        "additionalProperties": true,
      +        "properties": {
      +          "cohort": {
      +            "type": "string"
      +          },
      +          "periods": {
      +            "items": {
      +              "type": [
      +                "number",
      +                "null"
      +              ]
      +            },
      +            "type": "array"
      +          },
      +          "size": {
      +            "type": "number"
      +          }
      +        },
      +        "type": "object"
      +      },
      +      "type": "array"
      +    },
      +    "mode": {}
      +  },
      +  "required": [
      +    "data"
      +  ],
      +  "type": "object"
      +}
  2. Changed1 schema field changedv0.4.3
    • changedInput schema / properties / filters / items / properties / parameter / description
      Previous value: -"Filter dimension: browser, operating_system, language, country, region, city, device_type, referrer, hostname, pathname, page_title, querystring, event_name, channel, utm_source, utm_medium, utm_campaign, utm_term, utm_content, entry_page, exit_page, user_id. Note: user_id filter checks BOTH the device hash (user_id) and app-provided ID (identified_user_id)."New value: +"Filter dimension. One of: browser, browser_version, operating_system, operating_system_version, language, country, region, city, device_type, device_model, app_version, dimensions, referrer, hostname, pathname, page_title, querystring, event_name, channel, utm_source, utm_medium, utm_campaign, utm_term, utm_content, entry_page, exit_page, user_id, lat, lon, timezone, vpn, crawler, datacenter, company, company_type, company_domain, asn_org, asn_type, asn_domain, tag. Custom URL parameters use the prefix 'url_param:NAME' (e.g., 'url_param:campaign_id'). Note: user_id filter checks BOTH the device hash (user_id) and app-provided ID (identified_user_id). device_model and app_version are populated only for app-type sites tracked via SDK."
  3. First observedv0.5.2

TDQS

B3.4/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful semantics (cohort retention over time) but says nothing about date-range requirements, granularity, or how start/end dates interact with the pastMinutes alternatives.

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?

A single front-loaded sentence with no filler; the core purpose and output meaning are stated immediately.

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

Completeness4/5

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

An output schema exists, so return-value explanation is unnecessary, and the schema documents all inputs. The only gap is guidance on the temporal scope and how date parameters are expected to be used for a cohort analysis, which is minor.

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

Parameters3/5

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

Schema description coverage is 100%, so the seven parameters (siteId, date range, timezone, filters, pastMinutes overrides) are already fully documented in the schema. The description adds no parameter-level meaning of its own, which is acceptable given the baseline.

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

Purpose4/5

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

States a clear verb and resource ('Get user retention cohort analysis') plus the semantic content of the output ('how many users return over time periods'). It is distinguishable from analytics siblings like rybbit_get_overview or rybbit_analyze_funnel, but it never names or contrasts with those alternatives.

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

Usage Guidelines2/5

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

There is no when-to-use guidance, no prerequisites, and no mention of how this differs from funnel, session, or overview tools in the sibling list. The agent must infer the use case entirely from the phrase 'cohort analysis'.

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