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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered structurally. The description adds value by disclosing the per-symbol data returned, but says nothing about the overall response shape (single watchlist vs list), ordering, or behavior when the named watchlist does not exist. Solid but not rich behavioral context.

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?

Two sentences, zero filler: payload contents first, routing guidance second. The alternative-tool pointer is placed at the end where it belongs.

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-optional-param read tool with full annotation coverage, this covers purpose, payload, and routing. Minor gaps remain around the collection-level response shape and empty/unknown-name behavior, but nothing required to call it 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?

The single 'name' parameter is fully documented in the schema, including case-insensitivity and the default of all watchlists, so the schema does the heavy lifting. The description adds no additional parameter meaning beyond that, which lands at the baseline 3.

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 resource (the user's watchlists) and enumerates exactly what each entry contains — price, day change, market cap, P/E, sector, 1-year return, RSI, next earnings — so the agent knows the payload shape without opening anything. It also names the sibling tool market_query, making the boundary unambiguous.

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 gives the exclusion rule: for filters over a watchlist (with a concrete example, 'my Tech watchlist with RSI under 30'), use market_query instead. The when-not condition is concrete and tied to a named alternative.

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