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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false. The description goes beyond these by adding that the call is free (does not deduct search credits), does not modify the image, that access is logged, and that an unknown asset_id returns a tool error. These are valuable behavioral details not present in 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 about 100 words and every sentence contributes: purpose, return fields, usage routing, auth, cost, logging, error, and a rights warning. It is front-loaded with the core action and then packs relevant context. Slightly longer than minimal, but not padded.

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 carries the burden of explaining return values, and it does so by listing the fields (asset_id, title, source, dimensions, format, URLs, rights). It also covers the error case, auth requirements, cost, logging, and a pre-use caution. For a one-parameter read-only tool, this is complete.

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 the baseline is 3. The description adds a meaningful correctness hint—'Pass the ID unchanged, not a file URL'—and frames the parameter in the context of search results and saved assets, reinforcing the expected input beyond what the raw schema property description states.

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 ('Retrieve') and resource ('one known Lightdrift asset'), and explicitly distinguishes itself from the search tools by saying 'use the search tools to discover images.' It also ties the asset_id to the outputs of search_images and find_similar_images, making the relationship to siblings clear.

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 guidance ('inspect a selected image or retrieve a saved asset') and when-not-to ('use the search tools to discover images'). It also names a prerequisite (OAuth or API key) and a safety note (inspect rights before using the file).

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