scan_datastore_images

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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true, so the safety profile is covered. The description adds valuable context: it refreshes a local cache file, may be slow on large estates, and describes the return envelope (including a deprecated alias). This goes beyond what annotations convey and is consistent with them.

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 well-organized: a one-line purpose, a usage note, and a returns section. It front-loads the core action and packs the return format into a compact paragraph. While not as terse as the best examples, every sentence earns its place and there is no filler.

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 scan tool with one optional parameter and no output schema, the description explains the return envelope, the cache side effect, and the performance caveat. It gives the agent everything needed to decide when to call it and what to expect, making it complete for its complexity.

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 single parameter 'target' is fully described in the schema (coverage 100%) as 'Optional vCenter/ESXi target name from config.' The description does not add any additional meaning or syntax details about this parameter, so the baseline of 3 applies since the schema handles it completely.

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 opens with a specific verb-resource pair, 'Scan all accessible datastores for deployable images (OVA/ISO/OVF/VMDK)', and immediately contrasts itself with browse_datastore, so an agent can distinguish it without opening the schema. It names the exact image types it looks for, which is concrete and 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?

It explicitly states the triggering condition ('Use this when you do not know which datastore holds an image') and the alternative ('prefer browse_datastore once you do'), including a rationale about performance ('walks every datastore and may take minutes on a large estate'). This is textbook when/when-not guidance.

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