snapshot_aging

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint. The description adds meaningful behavioral detail beyond that: the return shape is a 'rollup, not the list envelope,' and it discloses that est_size_mb is a 'lower bound' with an explanation of why (delta-disk growth not separable). It also flags that deletion belongs elsewhere. This adds value beyond annotations without contradiction.

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 compact, with the primary purpose and use case front-loaded in the first two sentences. Every sentence earns its place: purpose, usage, return structure, field caveats, and read-only note. No 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?

Despite having no output schema, the description fully explains the return structure (including fields like total_snapshots, old_snapshots, vms_with_snapshots, threshold_days, snapshots[], hint) and caveats about est_size_mb. It also covers the only behavioral caveat (read-only, no deletion). For a tool with 4 optional parameters and no output schema, this is complete.

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 100%, so the schema fully documents all four parameters. The description does not add new parameter-level semantics beyond what the schema already provides, hence the baseline of 3 is appropriate.

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 verb (sweep) and resource (ALL VMs' snapshots) with a clear purpose (flag old/sprawling ones). It distinguishes itself from the sibling vm_list_snapshots by saying 'prefer vm_list_snapshots when you only care about one VM.' This leaves no ambiguity about what the tool does.

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 explicitly says 'Use this for fleet-wide snapshot sprawl' and directly names the alternative tool with the condition to switch. This is a textbook example of usage guidance, covering both when and when-not to use this tool.

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