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

Annotations already cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false), so the bar is lower. The description usefully adds a scope exclusion ('never performs OCR or plan reading'), but says nothing about idempotency dedupe behavior despite requiring idempotencyKey, nor about failure modes when reservation validation fails or what happens to file metadata after registration.

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 tight sentences with the precondition front-loaded and the scope exclusion clearly appended. Nothing is wasted, though the terseness comes at the cost of the parameter detail noted elsewhere.

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?

A six-required-parameter mutation with no output explanation needed is left almost entirely undocumented; only the sequencing precondition and the OCR exclusion are given. For a registration call where idempotency and URL format matter, this is materially incomplete even though annotations cover safety.

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 0% across six required parameters, so the description carries the full burden and fails to do so. It never explains idempotencyKey, hostFileUrl, fileSize or mimeType, leaving an agent to guess formats and semantics for every input it must supply.

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?

Uses a specific verb+resource pair ('Registers a host-provided file') and adds a precondition ('after upload reservation validation'), which distinguishes it from the reservation step in prepare_job_evidence_upload. It stops short of naming siblings explicitly, and the jargon 'host-provided' slightly obscures what is actually being registered.

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 phrase 'after upload reservation validation' implies sequencing, suggesting this is the second step following an upload reservation, but no alternative is named and no when-not condition is stated. An agent must infer that it should not be called as a first step or on files not previously reserved.

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