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

Annotations already cover read-only and open-world, but the description adds meaningful non-structured context: the 1-credit cost, the fact that only public data is available, and the differing payloads for creator/business vs personal accounts. It stops short of stating failure behavior for unknown or private handles.

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?

Three tight sentences, front-loaded with the identity of the tool, then return shape, then cost. Nothing is repeated from the name or schema and every clause carries information.

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 no output schema, the description correctly shoulders the burden of describing return values, and does so per account type. Remaining gaps are edge-case behavior (private/deleted handle) and the undocumented cache_max_age parameter, both minor for a simple read tool.

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 50%: handle is well documented in the schema, while cache_max_age is undocumented in both places. The description implies a handle-based lookup but adds no syntax or format detail beyond the schema, so the baseline 3 holds; it does not compensate for the cache_max_age gap.

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+resource ('User profile. Public Snapchat profile') and immediately enumerates what is returned, including the account-type split. The snapchat_ prefix plus the profile framing makes it trivially distinguishable from snapchat_spotlight and snapchat_spotlightComments.

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 only implied: the description signals 'public profile lookup' so an agent can infer when it applies, but there is no explicit guidance on when to prefer it over other Snapchat tools or what to do when a handle is private/nonexistent. No exclusions are stated.

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