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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered; the description nonetheless contributes the licensing/cost fact ('free') and an obligation attached to the returned data (credit line must be reproduced in READMEs). The trailing 'Read-only' partly restates the annotation, and there is no mention of behavior for an unknown or stale id, which keeps this below a 5.

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 payload content and then the practical credit-line instruction — nothing is buried. The long mid-sentence enumeration of returned fields is dense and marginally overlaps the output schema, and the closing 'Read-only, free' is a partially redundant tail.

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 an output schema present, enumerating return fields is not strictly required, and parameters are fully documented, so the description is adequate. What it does not address is the one behavior an agent must handle: what happens when an id does not resolve (error vs empty result), which matters for a lookup that is typically called in a loop over search hits.

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?

There is a single parameter at 100% schema coverage, and the schema already explains its format and provenance ('an asset id from search_assets, e.g. "ph:wooden_barrel_01"'). The description adds no further meaning about id, so the baseline 3 for a fully documented single parameter applies.

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 and resource ('Full details for one library asset') and then enumerates exactly what that detail set contains: per-format download URLs, size in metres, up axis and origin, texture maps, credit line, related assets, import notes. That enumeration plus the singular 'one asset' clearly separates it from the sibling search_assets, which finds assets rather than returning a single record.

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?

Usage context is clear: this is the fetch-detail step taken once you have an id, and the description adds a concrete downstream instruction ('when you write credits or a README... include its credit line'). It stops short of an explicit when-not or a named alternative, though the schema's pointer to 'an asset id from search_assets' covers the routing gap.

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