get_time_series

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

Annotations already declare the tool read-only, open-world, and idempotent. The description adds value beyond that by disclosing the response size (0-100 values) and that volume may be included when available. It also reveals behavior under rate limiting/quota exhaustion, telling the agent to inform the user their plan limit is reached. No contradiction with 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?

Every sentence earns its place: core behavior, use cases, sibling routing, and error behavior are covered in four short sentences. The critical scoping constraint ('one keyword and one source') is front-loaded, and the sibling alternatives are clear and immediately actionable.

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 two-parameter read-only tool with a full output schema and 100% schema coverage, the description provides everything else an agent needs: purpose, use cases, exclusions, sibling routing, response limits, and error handling. Nothing essential 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%, so the schema already thoroughly documents both parameters, including detailed per-source keyword format rules. The description confirms 'one keyword and one source' but adds little semantic detail beyond the schema. Baseline 3 is appropriate since the schema carries the burden.

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 first sentence clearly states the tool returns a full historical series for one keyword and one source, which is a specific resource and operation. It also explicitly distinguishes itself from siblings: it is not for live trending boards (use get_top_trends) and not for most growth questions (use get_growth). This makes the tool's purpose unambiguous relative to the sibling set.

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 gives explicit when-to-use guidance ('Use for charting or custom math') and when-not-to-use guidance with named alternatives ('Not for live... (use get_top_trends)'; 'For most growth questions, use get_growth'). It also instructs the agent on quota/rate-limit handling, which is a rare and valuable usage detail.

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