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

Beyond the annotations (readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false), the description adds hard constraints: 8 MB cap, HTTPS-only, no redirects, no screen assignment, and that credentials are never uploaded. What it omits is the return shape and duplicate/retry behavior — what the agent gets back on success, or whether re-uploading the same URL duplicates state, which matters given idempotentHint=false.

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?

Every clause carries information, but it is delivered as one dense run-on block with no front-loaded separation of the two modes, so the credential behavior appears several sentences after the asset behavior. Restating the key-entry mode already implied by the title is minor waste; the real cost is scanability for an agent choosing between branches.

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?

With no output schema, the description should say what a successful call yields (asset URL/ID, or the portal instruction payload); it does not. Otherwise it is complete for a 6-parameter, enum-driven tool, covering scope limits, credential handling, and the required post-step with bdk_check.

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 a baseline of 3 applies, but the description adds meaning the schema does not: the 1024×1024 PNG/JPG envelope and no-transparency/no-animation rule for app_icon, and the fact that omitting purpose defaults to a non-validated image path. The customer-approval requirement on source_url is also substantively new relative to the schema text.

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 names a concrete verb and resource ('Import a direct public HTTPS PNG, JPEG or WebP image') and discloses the second mode ('kind:credential returns portal instructions'), plus an explicit non-effect ('this does not assign a screen'). The dual-mode purpose is clear, but the credential branch is buried mid-paragraph rather than stated up front, so an agent must read the whole block to see the tool does two different things.

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 gives explicit when-to-use alternatives ('Use the portal for local files and screens'), an explicit prohibition ('never use an unvalidated image as an icon'), a routing rule for the credential branch, and a follow-up step ('After portal credential entry, run bdk_check with run:true'). Push-service and App Store Connect preconditions are also stated, leaving little to inference.

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