Read SimVar

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds a useful behavioral detail beyond annotations: 'Returns the value together with the unit it was actually read in,' clarifying output flexibility. No contradiction exists.

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

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

Three short, purposeful sentences front-load the core action and then add return behavior and a practical usage hint. No filler or repetition of schema details.

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

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

Given the rich annotations, complete schema descriptions, and an output schema, the description is sufficient for a single-value read tool. It could mention batch or watch alternatives to fully orient the agent among siblings, but nothing essential to making a correct call is missing.

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

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

Schema description coverage is 100% and each parameter (name, unit, index) already has descriptive text with examples and defaults. The tool description essentially repeats the purpose covered by the schema without adding new parameter-level semantics.

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

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

The description states a clear action and resource: 'Read a SimVar value by name, in the requested unit.' This clearly identifies a single-value read operation and is distinct from the set/search lvar siblings, but it doesn't explicitly differentiate from the closely related msfs_get_simvars_bulk or msfs_watch_simvar.

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

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

It provides actionable routing: 'Use msfs_search_simvars first if you are unsure of the exact name or units.' This is useful and context-specific, though it stops short of naming other alternatives such as get_simvars_bulk for batch reads or watch_simvar for continuous reads.

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