Write SimVar

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

The description adds a meaningful behavioral detail beyond the annotations: it fails with a specific error if the sim rejects the write, rather than reporting success. This helps an agent understand failure semantics. The annotations already cover read-only, destructive, idempotent, and open-world traits, so the description supplements rather than repeats them.

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?

The description is two short sentences with no filler. The main action is front-loaded, and the error behavior and prerequisite are provided in the second sentence, both earning their place.

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?

The description covers the core operation, a key precondition, and failure behavior, while the annotations and output schema handle safety and return shape. It does not mention a requirement to be connected to the simulator, but that is likely implied by the tool family and sibling msfs_connect.

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%, so the input schema already documents all four parameters well. The description adds no additional parameter-level meaning beyond the schema, making the baseline 3 appropriate.

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 opens with the specific verb 'Write' and resource 'settable SimVar', which clearly identifies the operation and distinguishes it from sibling tools like msfs_set_lvar. The 'settable' qualifier adds precision about which SimVars are valid targets.

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?

The description gives explicit guidance: check the 'settable' flag with msfs_search_simvars before writing. This provides a clear precondition and context for correct use, though it does not name alternative tools or explicit when-not-to-use conditions.

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