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

No annotations are provided, so the description carries the burden of behavioral disclosure. It does disclose a notable behavior: it retrieves every image size and video stream, including each page of an idea/story pin, which is useful. However, it does not disclose potential rate limits, pagination behavior, or what happens for pins with no video streams. The billing note ('1 Credits') is present but is not a behavioral trait. Overall, it adds some context but leaves gaps.

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, focused sentence that front-loads the core purpose and includes the key detail about idea/story pin pages. The 'Group' and 'Billing' lines are extra metadata but are short and not redundant. It is efficient and well-structured, though the billing/group info could be considered noise.

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 read-only retrieval tool with 100% schema coverage and no output schema, the description covers the main purpose and a key edge case (idea/story pin pages). However, it does not mention what happens when a pin has no video streams, whether the response includes all metadata fields, or any rate-limit considerations. Given the tool's moderate complexity, the description is adequate but not fully 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 description coverage is 100%, so the schema already documents both parameters. The description adds no additional meaning beyond what the schema provides; it does not elaborate on the countryCode behavior or pinId format beyond the schema. Baseline 3 is appropriate since the schema does the heavy lifting.

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 ('Retrieves') and a precise resource ('every image size and video stream of a Pinterest pin... along with its title, creator and metadata'). It clearly distinguishes this from sibling tools by naming the platform (Pinterest) and the specific resource type (pin details), which is distinct from Facebook/Instagram/TikTok/YouTube siblings.

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 usage context by specifying what it retrieves (all image sizes and video streams, including idea/story pin pages), which helps an agent know when to select it. However, it does not explicitly state when to use this tool versus alternatives, nor does it mention any exclusions or prerequisites. The 'Group: Pinterest-Pin' hint provides some context but no explicit routing guidance.

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