Read VM Variable

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

With no annotations, the description's verb 'Read' conveys the key non-mutating behavior, which is important for safe tool selection. It does not describe error cases, prerequisites, or return behavior, but for a read primitive the core behavior is clear.

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?

A single, front-loaded sentence with no filler. It is appropriately sized for a simple read tool.

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?

For a three-parameter read tool with fully documented schema fields, the description plus schema supplies what an agent needs to invoke it. It could be more complete by naming the write counterpart and return value, but those are low-risk omissions.

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%; each parameter, especially var_type, has a meaningful description. The tool description itself adds no parameter detail, so the baseline 3 applies.

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?

States a clear action (read) on a clear resource (a variable from VM state), and the title reinforces it. It does not explicitly contrast with sibling vm_write_variable, so it stops short of full sibling differentiation.

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?

No guidance on when to choose this over alternatives; it does not mention vm_write_variable or other variable/guest-state tools. The only usage signal is implied by the verb 'read'.

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