Your watchlists and the symbols on each

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

Annotations cover readOnlyHint and openWorldHint, so the safety bar is already met; the description still adds real context by disclosing the auth requirement ('needs the account key') and the closed scope ('reads nothing but this account'), plus the return shape.

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?

Three tight sentences, front-loaded with the trigger condition, then return contents, then auth/scope. Every sentence carries information an agent needs.

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?

No output schema exists, yet the description characterizes the return payload (watchlist id/name/symbol count plus ordered symbols, conditional on include_symbols) and the auth requirement, which is everything needed to call this single-param read 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?

Schema coverage is 100%, so the baseline is 3, but the description adds value by stating the default behavior ('unless include_symbols is false') and that symbols come back 'in order', which the schema does not say.

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+resource (lists the account's watchlists and their symbols) and spells out the returned fields (id, name, symbol count). It is clearly distinguished from the sibling write tools add_watchlist_symbol and remove_watchlist_symbol.

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?

Explicitly says when to call it: when the user asks what is on their watchlist, which lists they have, or before adding/removing a symbol. That routes the agent relative to the add/remove siblings, though no sibling is named outright and there is no explicit when-not clause.

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