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

Annotations already declare readOnlyHint=true, and the description adds valuable context beyond this: 'inverted GDELT DOC 2.0 average tone', '14d global English firehose', 'keyless', 'daily' updates, and a specific output structure. This provides a transparent picture of data source and behavior 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 dense but well-organized, front-loading the core return value and output fields, then the usage guidance, and ending with an update frequency note. Every sentence adds useful information with minimal fluff.

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?

Despite no output schema, the description enumerates the key fields returned (score, regime, trend, etc.), and explains the data source and update cycle. The optional 'days' parameter is fully covered by the schema. Together, this gives the agent enough context to invoke the tool correctly.

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?

The schema fully documents the only parameter 'days' with description, min/max, and tier requirement, so schema coverage is 100%. The tool description itself does not add extra semantics for this parameter, so a 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?

The description clearly specifies the tool's function: 'Returns a 0-100 global news stress gauge' with a list of concrete output fields (score, regime, trend, etc.). It also distinguishes itself by mentioning the inverted GDELT tone and global English firehose, making it unique among siblings.

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?

Provides explicit usage context: 'Call when the user asks how negative or tense world news feels right now, whether media stress is rising, or when timing announcements...' This is clear and actionable. However, it does not mention alternatives or when-not-to-use, so it doesn't reach a 5.

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