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

Annotations already declare the tool safe (readOnly, idempotent, non-destructive). The description adds 'public' and 'Keyless' to clarify access needs, and 'real view/comment/share counts' specifies the metrics returned. This goes beyond annotations without contradiction.

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 that packs the purpose, scope, output type, and access requirement with no wasted words.

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 two-parameter read-only tool with complete schema and strong annotations, the description is adequate. It could mention pagination or order of results, but 'unified Post[]' hints at a standard list format.

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?

Input schema covers both parameters completely, including the clamping behavior for limit and the '@' expectation for username. The description adds no additional parameter-level details, so the schema is sufficient.

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 clearly specifies the resource (a creator's public Snapchat Spotlight feed) and the output (unified Post[] with real view/comment/share counts). It distinguishes from sibling tools by mentioning 'Keyless' and the platform-specific focus, but it lacks an explicit action verb like 'fetches' or 'retrieves'.

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: the description notes the feed is public and keyless, suggesting it is appropriate when no authentication is required. However, it does not explicitly state when to choose this tool over alternatives such as social_posts or social_profile.

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