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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the safety profile is covered. The description adds value beyond that by amplifying the blast radius ('EVERY object') and disclosing the dangerous bare-prefix matching behavior that could delete unrelated sibling keys — real behavioral context, not just a restatement.

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?

Three sentences, zero waste, front-loaded with the destructive scope, then the prefix gotcha, then the safety workflow. Every sentence earns its place.

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?

Annotations carry the safety/idempotency profile and there is no output schema to explain, so the description only needs to add operational context — which it does via scope, prefix risk, and the pre-check step. It could say more about partial-failure behavior, but it is complete enough for correct invocation.

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 coverage is 100%, so the baseline is 3. The description goes further by explaining WHY keyPrefix must end in '/' — a bare prefix like 'old-logs' would also match 'old-logs-archive/...' — adding rationale and risk semantics the schema's terse description does not convey.

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?

States a specific verb and resource with clear scope: 'Permanently deletes EVERY object under a prefix.' This implicitly distinguishes it from delete_object (single) and delete_objects (list), though it does not name those siblings explicitly, so it lands just short of a 5.

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?

Provides a concrete prerequisite workflow: 'Call list_objects first and show the user what will be deleted before calling this.' Clear when-to-use context, but it never names an alternative tool (e.g., delete_object for a single key) or a when-not condition, so no explicit exclusion guidance.

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