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

Beyond the annotations (idempotent, non-destructive, closed-world write), it discloses the required OAuth scope write:shortlist and what to do on a missing scope, that existing entries are retained, and that each ticker is saved independently with partial failures reported so only failed tickers are retried. These are non-obvious traits an agent could not infer from the schema. It stops short of describing the response payload shape, which matters since there is no output schema.

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?

Five short sentences, front-loaded with purpose and scope, followed by prerequisites, idempotency, failure semantics and exclusions. Every sentence contributes a distinct, actionable fact with no filler.

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 single-parameter write tool with no output schema, the description still covers auth requirements, idempotency, merge-vs-replace behavior, partial-failure reporting and retry strategy. Nothing an agent needs to invoke it correctly, or to interpret a mixed success result, 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% and already enforces minItems 1, maxItems 20, the ticker pattern and an example, so the description's '1-20 exact ... tickers' largely restates it. It does add the constraint that tickers must be exact Bullrun stock or ETF listings resolved via search_stocks/search_etfs, which is semantic guidance the pattern alone cannot convey.

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 (add), resource (Research Shortlist), and precise scope: 1-20 exact listing tickers for the signed-in user. It also explicitly contrasts itself with adjacent capabilities (portfolio creation, monitoring, notifications), so it is separable from siblings like create_portfolio_draft or list_research_shortlist.

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 the triggering condition ('when the user asks to save them'), a prerequisite step ('Resolve ambiguous names with search_stocks/search_etfs first'), and explicit exclusions ('Does not create a portfolio, schedule monitoring or send notifications'). An agent knows both when to call it and which siblings to route to instead.

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