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Connecting AI Tools (Claude & ChatGPT)

Connect your HOSHIDOU charts to Claude or ChatGPT, read your horoscope in conversation, and call any of the MCP endpoints — full reference included.

On the 星導き (Hoshimichibiki) plan — free during the beta — you can connect your HOSHIDOU account to AI tools such as Claude and ChatGPT. Once connected, the AI reads your natal chart and transits to the arcsecond and interprets them with you in conversation. HOSHIDOU does the calculation; the AI you connect does the reading.

The connection uses MCP (Model Context Protocol). HOSHIDOU exposes an MCP server at https://app.hoshidou.com/api/mcp. Register that URL in a supported AI client and you can manage birth data, calculate charts, and read and write memos from inside the conversation.

What you need

  • A HOSHIDOU account on the 星導き plan
  • An AI client that supports custom connectors (remote MCP): Claude (Pro / Max and similar) or ChatGPT (Plus / Pro / Business / Enterprise / Edu)

Connect from Claude

In Claude you add HOSHIDOU as a custom connector. The screens differ a little by plan. For the full steps see Claude’s help article Get started with custom connectors using remote MCP. The essentials:

On Pro / Max (individual plans)

  1. Open “Customize > Connectors”.
  2. Click ”+” then “Add custom connector”.
  3. Enter https://app.hoshidou.com/api/mcp as the remote MCP server URL.
  4. Click “Add”.
  5. The HOSHIDOU sign-in screen opens. Sign in, review what will be shared, and approve.

On Team / Enterprise, an owner adds the connector with the same URL under “Organization settings > Connectors”, and members connect under “Customize > Connectors” by clicking “Connect”.

After connecting, enable HOSHIDOU for a given chat from the ”+” button at the lower left, then “Connectors”.

Connect from ChatGPT

In ChatGPT you enable Developer mode and register HOSHIDOU as a custom MCP app. See OpenAI’s ChatGPT Developer mode guide and Developer mode and MCP apps in ChatGPT. The essentials:

  1. Open “Settings > Apps”.
  2. Enable “Advanced settings > Developer mode”.
  3. Choose “Create app” and register the remote MCP server:
    • App name (anything recognizable, e.g. HOSHIDOU)
    • MCP server URL: https://app.hoshidou.com/api/mcp
    • Authentication: OAuth
  4. Save, then sign in on the HOSHIDOU screen, review what will be shared, and approve.

In a conversation, enable HOSHIDOU from “Developer mode” in the composer. Tools that change data (editing or deleting a profile, writing a memo) ask for confirmation before they run.

What you can do (endpoint reference)

Once connected, the AI can call the tools below from your conversation. The tool names are the formal names the AI uses internally — you just ask in plain language. Each tool has two example phrasings.

Most chart tools take a target person (profileId), and optionally a house system (Placidus, Whole Sign, and so on) and a zodiac (tropical or sidereal). Leave them out and the chart is computed with your default settings.

Managing birth profiles

list_birth_profiles — list saved people

Returns every person (birth profile) saved to HOSHIDOU. Use it before a calculation to confirm who you mean.

  • “List the people I have saved in HOSHIDOU.”
  • “Whose birth data do I have on file right now?”

create_birth_profile — add a person

Pass a name and birth date, and ideally a birth time and place, to create a new profile. Give the place as a name (e.g. Kyoto) and the coordinates and timezone are resolved for you. You can omit the birth time if it’s truly unknown. Planet positions are calculated for noon (12:00) at the birth place, so the Moon, which travels about thirteen degrees a day, can be off by six or seven degrees. Houses and angles are calculated from that same assumed noon, and they sit away from the real ones by a different order of magnitude: the Ascendant passes through a whole sign in about two hours, so the sign calculated from noon has about a one in twelve chance of being the real one. A chart built on that assumption carries meta.birthTimeAssumed set to true in the response. Astromap is the exception, since it needs an exact birth time: for a profile without one it returns an error instead of a chart. A profile saved without a time cannot, for now, be opened in the app’s chart screens (see Managing Birth Data).

  • “Add my mother: March 4, 1962, born in Kyoto, a little after 7am.”
  • “Add my friend Ayaka: November 20, 2000, 14:30, Tokyo.”

update_birth_profile — fix a saved person

Change any of name, birth date, time, coordinates, place, or notes. Only the fields you pass change. Even a small fix to the time can shift how the houses and angles read.

  • “Correct my father’s birth time to 5:40am.”
  • “Change the birthplace on the person I just added to Fukuoka.”

delete_birth_profile — remove a person

Permanently deletes a profile, along with its memos, saved charts, and reports. It can’t be undone. The AI previews what will be removed and only deletes after you clearly agree.

  • “Delete the test profile I made.”
  • “Remove the ‘former colleague’ data I don’t use anymore.”

Natal and timing charts

get_natal_chart — single-wheel (natal)

Computes a person’s birth chart to the arcsecond.

  • “Cast my natal chart and read my Saturn placement.”
  • “Calculate my natal chart in Whole Sign.”

get_transit_chart — transits

Computes the planetary positions for a date against a birth chart.

  • “Overlay today’s transits on my natal chart and point out what stands out.”
  • “Look at the transits for August 1, 2026 and tell me which aspects to watch.”

get_progressed_chart — secondary progressions

Computes the secondary progressed chart to a given date.

  • “Show me my progressions for now.”
  • “Where is my progressed Moon in 2027?”

get_solar_arc_chart — solar arc

Computes the solar arc directed chart to a given date.

  • “Give me my solar arc as of today.”
  • “Does anything hit my MC by solar arc next spring?”

get_triple_chart — triple-wheel (natal, progressed, transit)

Computes natal, secondary progressions, and transits as three rings with cross-aspects.

  • “Cast the triple-wheel — natal, progressed, transit — for today.”
  • “What aspects line up in my triple-wheel for December 2026?”

Returns

get_solar_return_chart — solar return

Computes the solar return for a given year, cast at the birth location. Read it for the year ahead from your birthday.

  • “Cast my 2026 solar return.”
  • “Read my solar return for what the year from this birthday looks like.”

get_lunar_return_chart — lunar return

Computes the first lunar return on or after a given date.

  • “Give me my next lunar return.”
  • “Calculate the first lunar return on or after July 2026.”

Relationship and two-person charts

get_synastry_chart — synastry

Overlays two saved natal charts and computes the cross-aspects between them.

  • “Run a synastry between me and my partner and explain the Sun and Moon aspects.”
  • “Cast my synastry with Ayaka.”

get_composite_chart — composite

Builds one relationship chart from the midpoints of two people.

  • “Cast the composite for me and him.”
  • “Read what our midpoint composite says about the relationship.”

get_composite_transit_chart — transits to the composite

Computes the transits to two people’s composite for a given date — the timing layer of the relationship.

  • “Read our year ahead through the transits to our composite.”
  • “What transits are hitting our relationship in 2026?”

Place charts

get_astromap_chart — astrocartography (relocation)

Computes each planet’s MC/IC/AC/DC lines and the parans where they cross, mapped across the Earth. Requires a known birth time.

  • “Cast my astromap and tell me where my Venus lines run.”
  • “If I were to relocate, which places look good by the relocation lines?”

Reading saved charts

list_saved_charts — list saved charts

Lists your saved chart snapshots.

  • “List my saved charts.”
  • “Do I have any charts saved from before?”

get_saved_chart — read a saved chart

Loads a saved snapshot, including its full calculation data.

  • “Load the calculation data from the chart I just saved.”
  • “Show me what’s in that snapshot again.”

Reading reports

list_reports — list reports

Lists your completed AI reports (read-only; does not generate).

  • “List my completed reports.”
  • “Do I have any past reports?”

get_report — read a report

Loads the full text of a given report.

  • “Load the full text of last month’s report.”
  • “Summarize what that report said.”

Ephemeris

get_monthly_ephemeris — monthly ephemeris

Returns planetary positions and key events for a given month.

  • “Show me the planetary movements for August 2026.”
  • “What are the main planetary events next month?”

get_voc_moon — void-of-course Moon

Returns the void-of-course Moon periods for a given month.

  • “Tell me the void-of-course Moon times for August 2026.”
  • “When is the Moon void this month?”

Memos

create_memo — save a memo

Saves a memo to a person’s notebook. Pin it to a planet or aspect, or keep it as a general note. Memos the AI writes are marked so you can tell them from your own.

  • “Save this note about my Sun–Saturn aspect.”
  • “Record a general note on this person: ‘first met in summer 2025’.”

list_memos — list memos

Lists the memos for a person. You can filter by a specific planet or aspect.

  • “List the memos attached to me.”
  • “Are there any memos pinned to this person’s Saturn?”

What gets shared

Revoking access

  1. Open “Connected apps” in your account settings.
  2. Choose “Revoke” on the connection you want to remove.

Revoking disables that connection’s access immediately. To use it again, connect once more with the steps above. You can also remove the connector from the Claude or ChatGPT side in their own connector settings.