Search the Oceanum Datamesh catalog for datasets.

Catalog search only covers datasources accessible to the credentials used for this request; a datasource missing from the results either does not exist or is not accessible with these credentials, so do not report it as nonexistent.

Get the metadata for one datasource: coverage, coordinates and variables.

The default view keeps every field of the full record but reduces each variable and coordinate to its dims, shape, dtype, units, long_name and standard_name, clips the description and long attribute values, caps global attributes. On very large records it sheds attributes and then per-variable details (the note says which), but every variable name is always listed.

Dry-run a query: report the result size WITHOUT downloading any data.

Always stage before retrieving data you have not sized. The response says whether the result is small enough for query_data to return inline, and echoes the canonical query. With limit plus time_resolution or aggregate_operations the reported size is that of the unlimited result (limit is applied after resampling), so it is an upper bound.

A variable given as the exact CF standard_name of exactly one of the datasource's variables (e.g. "sea_surface_wave_significant_height" for "hs") is resolved to that variable; the response then includes resolved_variables ({requested: used}) and echoes the resolved names.

Query a datasource and return small results inline.

The query is staged first; results larger than the inline limit are not downloaded (datasets are summarized lazily, tabular queries are refused with alternatives), and results above 1 GB are refused with narrowing advice and each variable's dims, unless limit is combined with time_resolution/aggregate_operations (the limited slice may be small, so a dataset is then opened lazily). Use stage_query to size a query before calling this.

Inline values are a preview when preview is true (returned of total records): never compute statistics from a preview; use aggregate_operations or time_resolution instead.

limit keeps the last N records (Datamesh semantics: the last N steps along time/ensemble). Combined with time_resolution or aggregate_operations, limit is applied by this server AFTER resampling/aggregation (to the last N resampled steps, or the last N rows of a table) rather than sent to Datamesh. A limited result is a subset of the requested range, so it is flagged as a preview, with a limit_note.

A variable given as the exact CF standard_name of exactly one of the datasource's variables (e.g. "sea_surface_wave_significant_height" for "hs") is resolved to that variable; the response then includes resolved_variables ({requested: used}) and echoes the resolved names.

Export the FULL result of a query — the data never enters the conversation.

Behavior depends on how the server is running:

• Hosted (http/sse): returns a time-limited, self-authenticating gateway download_url (choose format via format); path is ignored. Fetch the URL out-of-band — it needs no credential, so treat it as a secret. When the response includes expires_at or max_uses, fetch it before expires_at and at most max_uses times. Refused above the hosted export cap, and for limit combined with time_resolution/aggregate_operations.

• Local (stdio): writes the result to the local file path (required) and returns that path. Gridded datasets stream to NetCDF; tabular results write Parquet or CSV, as do datasets small enough to flatten into a table (e.g. point time series). Refused up front if the result exceeds the local export cap or the destination's free disk space. With limit plus time_resolution/aggregate_operations, the last N resampled steps are written.

The size is checked before anything is exported, whether or not stage_query was called. An export writing more than 1 GB in the chosen format (CSV text is about 3x; locally, a dataset written as CSV/Parquet is sized as the flattened table, and a limited one on its limited slice) is refused unless confirm_size_bytes equals that size (on hosted, within 5%, since the download stage is sized separately): ask the user first. The refusal states the exact value. The server cannot see whether the user was asked, so this is advisory: it forces an explicit, size-aware step. The export caps limit the transfer, not the size of each file: never split a refused request into parts to get under them.

A variable given as the exact CF standard_name of exactly one of the datasource's variables (e.g. "sea_surface_wave_significant_height" for "hs") is resolved to that variable; the response then includes resolved_variables ({requested: used}) and echoes the resolved names.

Summarize an entire datasource.

Gridded datasources are opened lazily (no data download). Tabular datasources are downloaded only if under the inline size limit; use query_data with filters to retrieve larger ones.

Update metadata properties on an existing datasource.

Only the provided fields will be updated; others remain unchanged. Not available when the server runs with OCEANUM_MCP_READ_ONLY set.

List files and directories in Oceanum cloud storage.

Check if a file or directory exists in Oceanum storage.

Read the contents of a text file from Oceanum storage.

Write text content to a file in Oceanum storage.

Creates the file if it doesn't exist, overwrites if it does.

Delete a file or directory from Oceanum storage.

Get metadata about a file or directory in Oceanum storage.