vsan_capacity

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

Annotations already set readOnly, destructive, idempotent, and openWorld hints. Description adds specific details: no side effects, graceful handling of vSAN disabled state (returns vsan_enabled=false with explanation), and error only on cluster name not found. This goes beyond annotations to fully describe behavior.

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 tightly written with every sentence earning its place: purpose, return shape, error handling, sibling differentiation, and parameter explanation—all in a compact paragraph. No filler or redundancy.

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 no output schema, the description includes the return structure and error cases. Two parameters are fully explained. Sibling tools are mentioned, and the description covers all aspects needed for correct invocation and result interpretation.

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?

Despite 0% schema description coverage, the description fully explains both parameters: cluster_name must be exact vCenter name and errors if not found; target is optional with default config. This adds crucial meaning absent from the schema's minimal type/title fields.

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?

Description starts with '[READ] Get space usage of a cluster's vSAN datastore for capacity planning,' clearly stating verb, resource, and purpose. It distinguishes from siblings vsan_health and list_all_datastores, making the tool's role unambiguous.

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?

Explicitly states when to use vsan_health for disk-group/host details and list_all_datastores for non-vSAN datastores. Also explains the error behavior (no error on vSAN disabled, only on missing cluster), providing clear guidance on when this tool is appropriate.

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