session_set_variable

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

With no annotations provided, the description carries full burden but offers limited behavioral insight. It implies a mutation operation ('Set'), but doesn't disclose effects like whether changes persist, require specific permissions, or affect session state. No rate limits, error conditions, or output details are mentioned, leaving significant gaps in transparency.

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 efficiently structured with a clear purpose statement followed by parameter explanations in a bullet-like format. Every sentence adds value, though the 'Args:' section could be integrated more smoothly. It's appropriately sized for a simple tool without unnecessary elaboration.

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 3 parameters with 0% schema coverage and an output schema present, the description provides basic but incomplete context. It covers parameter purposes minimally and relies on the output schema for return values, but as a mutation tool with no annotations, it should better explain behavioral implications and usage scenarios to be fully adequate.

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 0%, but the description adds basic semantic context for all 3 parameters: 'variable' as the name, 'value' as the content to set, and 'session_id' with optionality for active sessions. This compensates somewhat for the schema gap, though it lacks details on variable naming conventions, value formats, or session ID specifics.

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 clearly states the action ('Set the value') and target resource ('an iTerm2 session variable'), making the purpose immediately understandable. However, it doesn't explicitly differentiate from sibling tools like 'session_get_variable' beyond the obvious set/get distinction, missing an opportunity to clarify when to use each.

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 provides minimal guidance, only noting that 'session_id' can be omitted for the active session. It lacks explicit when-to-use instructions, prerequisites, or comparisons with alternatives like 'session_get_variable' or other session manipulation tools, leaving the agent to infer usage context.

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