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

With no annotations provided, the description carries full burden for behavioral disclosure. It explains the clustering behavior (related stories grouped into discrete events) and the three modes (recent, ticker-filtered, eventid drill-down). However, it does not disclose return format, pagination limits, or whether events are deduplicated across calls. The description adds valuable context about the clustering concept, but lacks details on output structure or data freshness.

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 sentence but dense with information. It front-loads the core concept ('Clustered crypto headline events') and immediately explains the grouping behavior and usage modes. It is efficient, but the sentence is slightly long and could benefit from a clear break (e.g., a colon or period) to separate the 'what' from the 'when to use'. Still, every phrase earns its place.

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 3-parameter optional tool with no output schema, the description covers the main modes of use (recent, filter, drill-down) and provides a clear use case. It does not describe the shape of returned events or how pagination interacts with clustering, but given the tool's moderate complexity and the lack of an output schema, the description is reasonably complete. It falls short of a 5 because it omits any mention of result ordering, event metadata, or limits.

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 0%, so the description must compensate for the three parameters. It mentions 'fetch recent events' (implying page), 'filter by ticker' (tickers), and 'drill into one eventid' (eventid). This gives functional meaning to each parameter beyond the bare schema types. However, it doesn't specify the expected format for tickers (e.g., comma-separated, single ticker) or the page size, leaving some ambiguity.

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 states the tool's function: 'Clustered crypto headline events — related stories grouped into discrete events'. It specifies the resource (crypto headlines), the action (fetch events, filter by ticker, drill into eventid), and distinguishes from raw headline lists. It also differentiates from siblings like tengu_v3_intel_news_crypto and tengu_v3_news_crypto_latest by emphasizing the clustered 'events' grouping.

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?

The description explicitly instructs when to use: 'Call this when the user asks what distinct news events hit a coin rather than a raw headline list.' This provides a clear usage directive and implicitly contrasts with raw headline tools. It also enumerates the available operations (fetch recent, filter by ticker, drill into eventid), making it easy for an agent to choose this tool over alternatives.

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