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

Annotations already signal destructiveHint=true and readOnlyHint=false, and the description adds meaningful context beyond that: it stores the file for fax delivery and warns that file bytes must not pass through the model for chat flows. This extra behavioral context is valuable, though it could have disclosed more about storage semantics.

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?

The description is front-loaded with the primary purpose and usage restriction, then provides the alternative flow. It is slightly dense and includes some repeated warnings, but every sentence contributes practical guidance and no irrelevant content is present.

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 tool with a full output schema, complete parameter descriptions, and annotations covering mutation behavior, the description covers the remaining important context: automation-only usage, the required next step, the chat-flow alternative, and side effects. Nothing essential is missing 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 description coverage is 100%, so the input schema already documents all six parameters including pipeline_id, file_content, and user_id constraints. The description does not add much parameter-level meaning beyond the schema, which matches the baseline of 3.

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 states a specific verb and resource: upload document bytes as base64 for non-chat integrations, with a clear follow-up step (call send-fax-uploaded with the returned path). It also distinguishes this tool from chat-related flows, so an agent can tell it apart from request-file-from-user and pipeline_start without opening schemas.

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?

It explicitly says 'Automation-only' and 'NEVER use this in chat', then names the correct chat flow: pipeline_start, list-numbers, list-contacts, then request-file-from-user. This gives both when-to-use and when-not-to-use guidance, plus the exact alternative path.

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