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

Annotations only declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false; the description adds genuinely useful traits beyond that: a side-effect write test before creation, best-effort cleanup ('deleted when possible'), conditional success/failure tied to the disabled flag, and a promise that the response excludes secret access keys. This materially exceeds what annotations alone provide.

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?

Four dense sentences, front-loaded with the primary action. Every sentence earns its place: purpose, cleanup caveat, enable/disable condition, and response-content guarantee. No repetition of schema content.

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 the tool's complexity (7 provider variants, nested required fields, conditional secrets), the description plus a 100%-covered schema and an output schema cover everything an agent needs. Prerequisites like bucket existence and IAM trust policy live in the schema; the description supplies the behavioral glue (test flow, cleanup, conditional failure, no secrets in response).

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 carries parameter documentation, giving a baseline of 3. The description adds only marginal parameter meaning by clarifying the disabled flag's interaction with test results — a nuance the schema partially states ('Enabling requires a successful connection test'). No additional syntax or provider-specific info is needed from the description.

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 and resource — 'Creates a storage destination' — and adds a distinctive behavior (testing a write to the bucket) that sets creation apart from the update/get/delete/list storage-destination siblings. An agent can tell this from create_proxy, create_template, and update_storage_destination without opening the schema.

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 gives clear conditional guidance: enabled destinations require a successful test while explicitly disabled destinations may be saved with a failed test. It does not explicitly name alternatives such as update_storage_destination for modifying existing destinations, but the create verb and clear context make the intended use evident.

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