Add Stocks to Watchlist

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

Annotations already declare idempotentHint=true, readOnlyHint=false, and destructiveHint=false. The description adds the concrete idempotent behavior ('adding a stock that's already followed is a no-op') and clarifies that it operates on the user's personal watchlist, adding context beyond the annotations. There is no contradiction with the 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?

The description is concise and well-structured: a clear opening sentence, three bullet-pointed use cases, and a helpful post-action tip. It is front-loaded with the core purpose and every sentence adds value, avoiding unnecessary verbosity.

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 simple one-parameter tool with no output schema, the description covers the essential information: purpose, idempotency, use cases, and a follow-up recommendation. It doesn't mention error handling or confirmation responses, but these are not critical for a low-complexity mutation tool, and the provided guidance is sufficient for an agent to invoke it 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 input schema fully documents the only parameter 'symbols' with a description and example, achieving 100% schema coverage. The description's use cases show sample symbol lists but do not introduce additional semantic meaning about the parameter's format or constraints beyond what the schema already provides, so a baseline score of 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 states the action 'Add one or more stocks to the user's watchlist' with a specific verb and resource, and differentiates from siblings like remove_from_watchlist and get_watchlist by focusing on the addition operation. The three use cases further specify the intent, leaving no ambiguity about what the tool does.

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?

It provides explicit use cases (single add, bulk add, after user request) that clarify when to invoke the tool. It also includes a post-action suggestion to offer analysis. It doesn't explicitly mention alternatives or exclusions, but the sibling list and title make it clear that this is for watchlist additions, not portfolio operations, so usage context is sufficiently clear.

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