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

Annotations already declare destructiveHint=true and idempotentHint=false, and the description goes beyond them by stating the exact failure mode (key collision unless overwrite) and that overwriting is irreversible. It omits permission/auth requirements and anything about partial failure, but the added behavioral context is genuinely useful.

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?

Two sentences with zero filler, front-loading the core action and ending on the routing alternative. Every clause carries information the agent needs.

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?

Covers encoding, overwrite failure semantics, irreversibility, and the alternative path, which is sufficient for a write tool whose annotations carry the safety profile. Minor gaps remain around whether content is size-limited or what a successful write returns, but no output schema exists so return detail is not strictly required.

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 baseline is 3, but the description adds semantic weight the schema lacks: it explains the interaction between key collision and the overwrite flag and warns that the overwrite path is irreversible. The contentType and connectionId parameters are left entirely to the schema.

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 ('Writes UTF-8 text to an object') and immediately scopes the content type to text, distinguishing it from binary-oriented siblings. An agent can tell this apart from create_upload_link or copy_object without opening a 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?

Explicitly routes binary or large content to create_upload_link, which is a clear when-not condition naming the alternative. It does not address other plausible siblings (e.g., set_object_metadata, copy_object), so guidance is strong but not exhaustive.

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