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

Annotations already declare readOnlyHint, openWorldHint and non-destructive behavior, so the description's real contribution is the billing model: 1 credit per successful request including native empty results, scraper failures not charged, and a 10-credit minimum. It also discloses the public-data-only limitation and that repeated requests may re-purchase the same data, all of which goes beyond the annotations.

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 content is duplicated almost verbatim three times, and fragments of page boilerplate ('Cosmos Collection API View Pricing', '1 credit per request') are pasted into the text. The core facts are good but roughly two-thirds of the wording is redundant, hurting front-loading and scannability.

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 one simple parameter, no output schema, and full schema coverage, the description covers what is returned, the data source, access limits, and cost behavior. Only the absence of sibling routing guidance and any pagination or error detail keeps it short of 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?

There is a single required url parameter with 100% schema description coverage, so the schema already carries its meaning ('Public Cosmos collection URL'). The description restates that the URL must be public but adds no format example, canonical URL shape, or rejection behavior, so the baseline of 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?

The description states a specific verb and resource ('Get a public Cosmos collection') and enumerates the returned fields (owner, description, cover, counts, public subcollections). It implicitly separates itself from social_cosmos_cluster_posts and social_cosmos_user_clusters by covering the collection object rather than its contents, but it never names a sibling explicitly.

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?

It sets a scope constraint - public Cosmos data only, with private or login-restricted content unavailable - which tells the agent when the call will fail. However, it names no alternative tool for posts, users, or search, so routing among the five cosmos siblings is left to inference from their names.

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