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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds real value beyond that: the data source (reddit), the per-headline sentiment taxonomy (bullish/neutral/bearish), the score field, and a concrete example response. It omits pagination, result caps, and rate limits, which keeps it short of 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?

Front-loaded with the core statement, then cleanly sectioned into Use when / Not for / Returns / Example. The example response is long but justified because no output schema exists. The 'Price' line is boilerplate rather than description content, the only real padding.

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 compensates by spelling out the return shape (headlines[] with title, url, sentiment, score, published_at) and giving a full sample payload, so an agent knows exactly what it will get. Nothing needed to call this two-parameter read tool 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 description coverage is 100% for both parameters (filter with its enum and default, currencies with its format example), so the schema already carries parameter semantics. The description's example only implicitly demonstrates the currencies argument and adds no detail on filter values; baseline 3 is appropriate.

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+source: 'Latest crypto news and community sentiment from r/CryptoCurrency for any token.' The scope (tokens) and provenance (r/CryptoCurrency subreddit) immediately differentiate it from generic news siblings like web_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?

Explicit 'Use when' clause gives the triggering condition (need recent headlines or community sentiment for one or more tokens), and 'Not for' names three alternatives by name — web_search, url_reader, fear_greed_index — with the condition that selects each. This is textbook routing guidance.

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