var_get_table_size

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

With no annotations provided, the description carries the full behavioral disclosure burden. It explains the return behavior for scalar values (null), which is a meaningful behavioral trait beyond the schema. It could additionally clarify error behavior for nonexistent paths, but for a simple getter this is adequate.

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 tightly written sentences with no filler. The purpose is front-loaded, followed by the key usage constraint and the edge-case return behavior. Every sentence contributes essential information.

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 single-parameter getter with full schema coverage and no output schema, the description provides enough context: what the tool does, what input it requires semantically, and what happens in a common edge case. It slightly underspecifies the exact return value for valid arrays, but 'size' reasonably implies a count.

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?

The schema already describes var_path as 'Full path to the variable', achieving 100% coverage. The description adds value by specifying that the path must point to an ICCAP_ARRAY variable, which clarifies what kind of variable the parameter should reference. This goes beyond the generic schema definition.

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 specific operation ('Get the size') on a specific resource ('ICCAP_ARRAY type variable'), and it immediately distinguishes itself from generic variable getters by clarifying the required value type. This clearly separates it from sibling getters like mvar_get and tablevar_get.

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 clear context for when to use the tool: only for variables holding an ICCAP_ARRAY value, such as those set via mvar_set with a JSON array. It also provides an exclusion by noting scalar string values return null, though it does not explicitly name an alternative tool for non-array variables.

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