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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds genuinely non-obvious behavior: the keyless demo only works with sandbox identities and suggests a test handle. It stops short of noting auth requirements or rate limits.

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?

Front-loads what the tool returns, then when to use it, then the selector constraint and demo caveat. Every sentence earns its place 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?

An output schema exists, so return values need no explanation. For a 4-parameter read tool, the description covers purpose, usage, selector semantics, and environment caveats completely.

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% and the schema itself already states the 'pass exactly one of' constraint in the username field. The description's parameter section largely restates the schema (one-of selector, address returns owner), adding little beyond structured data, so the baseline 3 applies.

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 (CabalSpy ID profile of a crypto trader) and enumerates the returned fields (X account, Telegram, KOL badge, verified wallets, 7-day activity), which lets an agent distinguish it from siblings like csid_kols or csid_leaderboard. The verb+resource is 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?

Gives concrete usage intent ('check who someone is and whether a trader really owns the wallets they claim') plus two illustrative example queries, which is strong context. However, it never names an alternative or a when-not-to-use condition, even though the address mode overlaps with the csid_wallet_owner sibling.

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