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

With no annotations, the description carries full burden but provides minimal behavioral insight. It mentions the resource type and accessibility but omits critical details like pagination behavior, rate limits, authentication requirements, or what 'list' entails (e.g., returns metadata vs. full values). For a read operation with zero annotation coverage, this is inadequate.

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 a single, efficient sentence with zero waste—front-loaded and to the point. Every word contributes to defining the tool's purpose without redundancy or fluff.

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 2 parameters with 0% schema coverage, no annotations, but an output schema exists, the description is incomplete. It covers the basic purpose but lacks parameter explanations and behavioral context. The output schema mitigates some gaps, but for a list operation with undocumented parameters, more detail is needed.

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%, so the description must compensate but adds no parameter information. It doesn't explain 'limit' (e.g., pagination or max results) or 'project_id' (e.g., filtering scope), leaving both parameters undocumented. With 2 parameters and no schema descriptions, the description fails to provide necessary 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 clearly states the verb ('List') and resource ('instance variables'), specifying they are 'key-value pairs accessible across all workflows.' It distinguishes from siblings like 'get_variable' (singular) or 'create_variable,' but doesn't explicitly contrast with other list tools like 'list_workflows' or 'list_tags.'

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 use this tool versus alternatives is provided. It doesn't mention prerequisites (e.g., needing a project context) or compare with similar tools like 'list_workflows' for workflow-specific variables. The description implies a broad scope ('across all workflows') but lacks explicit usage context.

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