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

Discloses non-obvious behaviors well beyond the annotations: omitted settings are cleared or reset, secret retention requires retain_secret_access_key: true with unchanged provider and key ID, changed connections and re-enabling trigger a bucket write test, failed tests prevent saving an enabled request, and plan downgrades restrict changes to disabling only. This complements rather than contradicts destructiveHint: true.

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?

Five sentences with zero filler: purpose is front-loaded first, followed by the clearing/secret caveat, the write-test side effect, the failure behavior, and the plan restriction. Every sentence earns its place and no information is repeated from the schema.

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 complex mutation tool with nested objects, seven provider variants, secret-handling rules, test side effects, and plan constraints, the description addresses every non-obvious behavioral aspect an agent needs. Combined with 100% schema coverage and an output schema, nothing critical for correct invocation is missing.

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 adds the global rule that omitted optional settings are cleared or reset, and highlights retain_secret_access_key's interaction with provider and access-key changes — cross-object semantics that the individual schema property descriptions do 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?

Opens with a specific verb-resource pair: 'Replaces a storage destination's configuration.' This clearly distinguishes it from the close siblings create_storage_destination, delete_storage_destination, get_storage_destination, and list_storage_destinations. The replacement semantics are 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?

The replace semantics and required id parameter make clear this tool modifies existing destinations, and the plan-downgrade note adds useful conditional context. However, it never explicitly names create_storage_destination as the alternative for new destinations, so it provides clear context without stated exclusions.

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