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

Annotations already declare readOnlyHint=true and openWorldHint=true, covering the safety and external-data aspects. The description adds the specific constraint that only 'public' pins can be fetched, which is valuable beyond the annotations. It does not contradict annotations, and the behavior is consistent.

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 a single, concise sentence with no wasted words. It front-loads the core action and the key qualifier 'public' upfront, making it immediately scannable for an agent.

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?

For a simple read-only tool with two documented parameters and no output schema, the description provides the essential information: it fetches a public pin by URL. It does not describe the response structure, but the tool name and parameters imply a pin object. The trim parameter is explained in the schema, so the description is reasonably complete for an agent to call it correctly.

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 description coverage is 100%, with both 'url' and 'trim' documented. The description simply says 'by URL', which reinforces the url parameter but adds no new meaning. The trim parameter is not mentioned, but the schema adequately explains it. The description meets the baseline for high schema coverage without enhancing parameter understanding.

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 uses a specific verb ('Fetch') and resource ('public Pinterest pin') and specifies the method ('by URL'). It clearly distinguishes from siblings like pinterest_board_pins_list (listing pins in a board) and pinterest_search_pins_list (searching pins), which serve different purposes.

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?

The description implies when to use it: when you have a specific pin URL. However, it does not explicitly mention alternatives or state when not to use it (e.g., 'For searching pins, use pinterest_search_pins_list instead'). The context is somewhat clear but not explicit about exclusions.

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