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

Annotations already declare the mutation profile (readOnlyHint=false, destructiveHint=true, non-idempotent). The description usefully adds the 10 MB ceiling and base64 encoding requirement beyond annotations, but never explains consequences of the destructive flag or how the channel binding is enforced. Adds some value but not rich behavioral context.

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 short sentences, zero filler, with the core capability and its size/format constraint front-loaded. Efficient, though it could name the alternative more concretely.

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 purpose, size limit, encoding, and channel scoping for a mutation tool with no output schema. It stops short of describing what 'bound to a channel' means operationally, and the destructive implication is left to the annotations.

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 all four parameters (including the private 'connection' credential) are documented in the schema, establishing a baseline of 3. The description's mention of base64 and the size cap loosely reinforces 'data' but adds no format or constraint detail the schema lacks.

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 ('Upload ... base64, bound to a channel') and adds concrete constraints (10 MB, base64, channel binding). An agent can tell it apart from siblings like message_send or page_create, though no sibling is named explicitly.

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?

'Prefer the HTTP upload endpoint for large files' gives a conditional when-to-use-elsewhere hint, which is genuine guidance. However it references an endpoint rather than a sibling tool and offers no exclusions or prerequisites, so usage is only partially covered.

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