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

Annotations already declare readOnlyHint/openWorldHint, so safety is covered, and the description goes further by disclosing credit cost, that repeated requests may re-purchase data, and the cache behavior with its 'cached': true / cached_at marker and 0-credit outcome. It is weakened by muddled pricing text that says both 'at least 10 Nexscope credits' and '1 credit per request'.

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 first sentence is strong and front-loaded, but the tail is bloated with pasted pricing boilerplate, a raw markdown documentation link, and duplicated credit figures that conflict with each other. Those sentences cost the reader more than they earn.

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?

There is no output schema, yet the description compensates by enumerating the returned fields and image variants, and it covers cost and caching. The one real gap is the contradictory credit figures, which leave an agent unsure of the actual price of a call.

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?

With schema coverage at 33%, the description does real work: it defines url as the pin URL, explains trim as a 'lighter response', and the caching paragraph explains what cacheMaxAge values mean in terms of cache age and credit cost. The cacheMaxAge explanation is indirect and tangled in boilerplate, but it adds meaning beyond the bare enum.

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 opening sentence names a specific verb and resource ('Fetches detailed information about a single Pinterest pin by URL') and enumerates what comes back (title, description, link, dominantColor, originPinner, pinner, image resolutions, pinJoin). The 'single pin by URL' framing implicitly separates it from social_pinterest_search, but no sibling is named explicitly, so it stops short of a 5.

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 is implied rather than stated: an agent infers it should call this when it already holds a pin URL. There is no explicit when-not guidance and no pointer to social_pinterest_search or social_pinterest_board as alternatives. The cost/caching paragraph gives operational context but not selection guidance.

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