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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the agent knows it is a safe public read. The description adds genuinely useful context beyond that: only public boards are accessible, and only ONE page of pins is returned rather than the full board. It stops short of explaining pagination mechanics, hence not 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: the capability first, then the alternatives. Zero filler and nothing repeated from the schema. Well front-loaded.

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, the description needn't spell out return values, yet it still names the key ones. For a two-required-parameter read tool with full annotation coverage, nothing an agent needs to call it correctly is missing.

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% and both parameters are already documented there, including that slug comes from the /{username}/{slug}/ URL. The description restates that username and slug are the lookup keys but adds no syntax or format detail beyond the schema, so the baseline 3 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?

States a specific verb (Fetch), resource (a public Pinterest board's metadata and one page of pin items), and even summarizes the returned fields (owner, cover, pin/follower counts, description). The 'public' qualifier and the routing sentence make it easy to tell apart from pinterest_user_boards, pinterest_pin, and pinterest_search.

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?

Explicitly names three alternatives and the condition that selects each: pinterest_user_boards to find boards, pinterest_pin for one pin, pinterest_search to discover pins. An agent has a full routing decision without opening any other schema.

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