cern-opendata-mcp-server

Get CMS Validated Runs

cern_opendata_get_validated_runs

Read-onlyIdempotent

Get a CMS validated-run (good-run) list, which certifies the luminosity sections that are good for physics in each run. Select it by a CMS collision dataset recid, a validated-run list recid, or a run period such as Run2012B (give exactly one of recid and run_period). Choose the full validation or the muons-only variant, and narrow to a run range; a dataset recid defaults the range to the first and last run the dataset lists. Returns the runs with their luminosity-section ranges and the list file download URL. CMS only.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "cern_opendata_get_validated_runs"
  }
}

Input Schema

Name	Required	Description
`limit`	No	Runs to return, 1-2000. A value above 2000 is served at 2000.
`recid`	No	A CMS collision dataset recid (its linked list is used) or a validated-run list recid (used as named): up to 12 digits, optionally after a lowercase experiment prefix (cms-93956). Give this or run_period.
`run_max`	No	Highest run to return, inclusive. Defaults with run_min for a dataset recid.
`run_min`	No	Lowest run to return, inclusive. With a dataset recid and neither bound set, run_min and run_max default to the first and last run the dataset lists; run_bounds echoes the range applied.
`variant`	No	full (every detector certified) or muons_only (certified for muon physics). Omitted: a list recid is used as named; a dataset recid or run_period selects full.
`run_period`	No	A CMS run period such as Run2012B, matched case-insensitively; 2012B also matches Run2012B. Give this or recid. cern_opendata_list_reference with topic run_periods lists them.

Output Schema

Name	Required	Description
`cap`	No	The page size (limit) applied to this call.
`list`	No	The selected list, when exactly one matched.
`runs`	No	Certified runs ascending within run_bounds, capped at limit; empty unless one list was selected.
`error`	No	Present when the call failed. Absent on success.
`shown`	No	Number of items returned on this page.
`notice`	No	Continuation, empty-result guidance or result caveats; absent when none.
`dataset`	No	The dataset, when recid named a dataset rather than a list.
`summary`	No	The whole selected list, before run_bounds.
`truncated`	No	True when more results remain past this page; notice says how to reach them.
`run_bounds`	No	Run filter range; absent when unbounded.
`totalCount`	No	Runs in the selected list inside run_bounds.
`matched_lists`	No	All selector matches in the requested variant. If several, none was read: call again with one recid.

Schema Changelog

Changes observed during successful MCP inspections.

Changed5 schema fields changedOct 30, 2026

changedOutput schema / properties / matched_lists / description

Previous value: -"Every list the selector matched in the requested variant. Several means none was read: call again with recid set to one of them."New value: +"All selector matches in the requested variant. If several, none was read: call again with one recid."

changedOutput schema / properties / notice / description

Previous value: -"Guidance for the next call: how to page on, why nothing matched and what to change, or a caveat about the results."New value: +"Continuation, empty-result guidance or result caveats; absent when none."

changedOutput schema / properties / run_bounds / description

Previous value: -"The run range runs was filtered to; absent when no bound applies."New value: +"Run filter range; absent when unbounded."

changedOutput schema / properties / run_bounds / properties / source / description

Previous value: -"input: run_min/run_max as given. dataset: both defaulted to the first and last run the dataset lists."New value: +"input: supplied run_min/run_max; dataset: both default to its first/last listed run."

changedOutput schema / properties / runs / description

Previous value: -"Certified runs, ascending, inside run_bounds and cut at limit; empty when no single list was selected."New value: +"Certified runs ascending within run_bounds, capped at limit; empty unless one list was selected."

Changed3 schema fields changedOct 18, 2026

changedInput schema / properties / limit / description

Previous value: -"Runs to return, 1-2000."New value: +"Runs to return, 1-2000. A value above 2000 is served at 2000."

changedInput schema / properties / limit / maximum
```
Previous value: -2000New value: +10000
```

changedInput schema / properties / recid / description

Previous value: -"A CMS collision dataset recid (its linked list is used) or a validated-run list recid (used as named): up to 12 digits, optionally after an experiment prefix (cms-93956); recid:N or a portal record URL also work. Give this or run_period."New value: +"A CMS collision dataset recid (its linked list is used) or a validated-run list recid (used as named): up to 12 digits, optionally after a lowercase experiment prefix (cms-93956). Give this or run_period."

First observedOct 2, 2026

TDQS

A4.6/5.0

Behavior4/5

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

Annotations already cover read-only/idempotent/open-world, so the description's added value is in resolution semantics: a dataset recid resolves via its linked list while a list recid is used as named, and a dataset recid defaults the run range to the dataset's first/last run. It notes run_bounds echoes the applied range, but does not mention result pagination/truncation behavior (the 2000 cap visible only in the schema).

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

Conciseness4/5

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

Front-loaded with what the resource is, then selection rules, then variant/range narrowing, then return content and scope. Dense multi-clause sentences carry real information, though the parenthetical about exactly-one plus the trailing 'CMS only' is slightly tacked on.

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?

For a 6-parameter, all-optional query tool with full schema coverage, an output schema, and annotations, the description covers purpose, selection constraints, defaults, and even return content (runs with luminosity-section ranges plus list file download URL). Nothing an agent needs in order to invoke it correctly is missing.

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 baseline is 3, but the description adds interpretation beyond the schema: the dual meaning of recid, the exactly-one-of constraint with run_period, and how variant defaults shift by selection mode (list recid used as named vs full for dataset/run_period). The narrowing role of run_min/run_max is described at a high level but the limit/paging parameter is not addressed.

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 and resource — 'Get a CMS validated-run (good-run) list' — and immediately explains what the resource represents (luminosity sections certified good for physics per run). The 'CMS only' scope and the recid/run_period selection axes distinguish it cleanly from generic siblings like get_records or search_records.

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 selection rules: give exactly one of recid and run_period, and it names the sibling tool (cern_opendata_list_reference with topic run_periods) for enumerating valid run periods. It also states which variant is chosen by default in each selection mode, leaving little to inference.

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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