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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, destructiveHint=false. The description adds extra context beyond annotations: 'No account access, no order placement or fund transfers. Not investment advice.' This goes beyond generic read-only declarations. However, it doesn't mention rate limits or authentication details, but given the strong annotation coverage, a 4 is appropriate.

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 two sentences (plus the [Read] prefix) and front-loads the primary purpose. Every sentence serves a purpose: first states what it does, second routes to alternatives and adds constraints. 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?

With an output schema present, the description doesn't need to explain return values. All 6 parameters are documented with useful details. Usage guidance, exclusions, and safety disclaimers are covered. Nothing an agent needs to call the tool correctly 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 coverage is 100% with detailed descriptions for each parameter. The descriptions add meaning beyond the schema by disambiguating from siblings (e.g., coin: 'not platform news index tickers (search_news)'). The description itself also reinforces the synthesized-answer behavior. This exceeds the baseline 3 for full coverage.

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 and resource: 'Search the open web and return a synthesized answer with cited external pages.' It also explicitly distinguishes from siblings by pointing to search_news and search_x for alternative use cases. An agent can clearly identify what this tool does without opening the schema.

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?

Gives explicit when-to-use guidance: 'Built-in headline lookup, news-item search, or briefing-style news list -> search_news. X/Twitter-only discussion or tweet evidence -> search_x.' Also includes context like 'Read-only public research data' and disclaimers about account access and investment advice, providing clear boundaries.

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