evidence_multipart_upload_start

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

The description adds behavioral context beyond annotations by stating that the tool returns upload coordinates and requires a pre-registered evidence. While annotations already indicate mutation (readOnlyHint=false), the description clarifies the session-starting nature and prerequisites without contradicting the annotations.

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 two concise sentences, front-loaded with the core purpose and return value, followed by usage condition and prerequisites. No wasted words, every sentence contributes to understanding the tool's role.

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 10 parameters and no output schema, this description is minimal but covers the essential purpose, when-to-use, and prerequisites. However, it lacks details on the structure of returned 'upload coordinates', how to proceed after starting, and what the many parameters mean, making it adequate but with clear gaps for a complex operation.

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?

With schema description coverage at only 30%, the description should compensate for the seven undocumented parameters. It only explicitly mentions evidenceId and fileName, and evidenceId's meaning is already covered in the schema. Most other parameters (e.g., title, createdBy, testimony, requiredTestimonyProviders) remain unexplained, leaving the agent without sufficient semantic guidance.

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 clearly states the tool starts a MULTIPART upload session for large evidence files, using a specific verb and resource. It distinguishes itself from alternatives by explicitly mentioning when a single presigned PUT is insufficient, which differentiates it from sibling upload tools like evidence_upload_url_create.

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 provides explicit when-to-use guidance ('Use when a single presigned PUT is not enough for the file size') and lists prerequisites (already-registered evidence and file name), naming specific sibling functions for obtaining the evidenceId. This effectively directs the agent on when to choose this tool over alternatives.

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