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Browse L-Var Catalogs

msfs_browse_lvar_catalog
Read-onlyIdempotent

Browse aircraft L-var catalogs to list panels or valid variable values, with auto-detection of the loaded flight sim aircraft.

Instructions

Browse the aircraft L-var catalogs.

Three levels, narrowing as you supply arguments:

  • no catalog resolved -- every available aircraft catalog

  • catalog only -- the panels in that catalog

  • catalog+panel -- the variables on that panel, with their valid values

With no 'catalog', the loaded aircraft is auto-detected: PMDG's own client-data-area probe first (authoritative -- confirms which SDK is actually running, independent of what TITLE/ATC_MODEL say), then every catalog's own title_pattern matched against TITLE/ATC_MODEL (the only mechanism for a third-party catalog dropped into data/). A successful detection acts as if that catalog had been passed explicitly, and 'message' names which of the two resolved it -- a probed detection is a materially stronger signal than a title-text match. When detection fails entirely, 'catalog' comes back None, 'message' explains why, and (with 'panel' also given) the panel is looked up across every catalog -- the first match is returned, but that is a guess, not a detection, and 'message' says so.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
limitNoMaximum results
panelNoPanel name to open, e.g. 'Signs', 'FCU', 'Electrical'. Omit to list the panels in the catalog.
offsetNoResults to skip
catalogNoCatalog key, e.g. 'pmdg_737', 'pmdg_777'. Omit to auto-detect from the loaded aircraft, or to list all available catalogs.
response_formatNo'markdown' for a table, 'json' for rowsmarkdown

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

  1. First observedv1.0.1

TDQS

A4.7/5.0
Behavior5/5

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

Beyond the readOnly/idempotent annotations, the description discloses subtle behavior: the two-stage auto-detection (client-data-area probe vs title_pattern match), what a successful detection means, and that a fallback cross-catalog panel lookup is 'a guess, not a detection.' This is exactly the kind of non-obvious behavior an agent needs to trust the result.

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?

The description is dense but organized: a one-sentence summary, a bulleted list of levels, then a focused explanation of auto-detection edge cases. Every sentence contributes behavioral or usage information; there is no filler.

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 tool with no required parameters and rich schema/output schema, the description covers the full decision space: all three narrowing levels, auto-detection success/failure, and the reliability caveat on fallback matches. Nothing an agent needs to call 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 the baseline is 3, but the description adds real meaning for the two key parameters: catalog and panel define the three browse levels, and the auto-detection semantics explain what omitting catalog does. It doesn't add detail for limit/offset/response_format, but the schema already covers those.

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?

The description opens with a specific verb and resource, 'Browse the aircraft L-var catalogs,' then defines three concrete output levels (all catalogs, panels in a catalog, variables on a panel). This distinguishes it from sibling tools like msfs_list_lvars or msfs_search_lvars, which operate on L:vars directly rather than the catalog hierarchy.

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

Usage Guidelines4/5

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

It gives explicit usage context: no catalog lists catalogs, catalog only lists panels, catalog+panel lists variables, and it explains auto-detection and fallback behavior. It falls short of a 5 because it never explicitly names alternative tools or states when not to use this tool.

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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