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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), yet the description goes further: public assets need no auth, password-protected assets return an error carrying the share URL, and client-encrypted content is returned as stored. These are auth, error, and content-fidelity behaviors the structured fields do not supply.

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 sentences, front-loaded with the return contract and then the routing plus edge-case behaviors. Every clause carries information and none is redundant.

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?

Although there is no output schema, the description enumerates the returned fields and covers the three edge cases an agent would hit (no auth for public, error for password-protected, as-stored for encrypted). Nothing needed to invoke or interpret the call is missing.

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% and the single parameter is already documented as a '12-character asset id returned by upload or search_gallery'; the description adds only the bare phrase 'by id'. With the schema doing the heavy lifting, this is the baseline case.

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 ('Fetch a single asset by id') and enumerates exactly what is returned (content, filename, creation time, share URL). It is clearly distinguishable from siblings like search_gallery and list_assets, which the description itself names.

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?

Explicitly routes the agent: 'Use search_gallery to find an id, or list_assets for your own uploads.' This tells the agent when to reach for this tool versus two named alternatives, leaving nothing to inference.

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