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 useful context beyond that: the result is ordered newest-first, and it requires your own CabalSpy API key tied to a CabalSpy ID instance (no demo), which is a real precondition an agent must know.

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 sentences, front-loaded with what the tool returns before the use case and the auth requirement. No filler; the example question is the single flourish and it earns its place by clarifying intent.

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?

Output schema exists, so return fields need not be explained, and the description still sketches the shape (token, position, ordering). Auth prerequisites and the user-scoping are stated; only explicit routing to competing siblings is left implicit.

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%, so limit, cursor, csid_id, instance, and username are all already documented in the schema. The description references the username form only via the example handle and adds no syntax or format detail beyond the structured fields; 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 verb+resource: 'All theses one CabalSpy ID user has posted, newest first, with token and the position they hold.' The user-scoping and newest-first ordering clearly separate it from token-scoped siblings like csid_token_theses and the global csid_latest_theses.

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 a concrete use case with a sample question ('judge a caller's track record: What has @CabalSpySol been bullish on, and did it work out?'), which tells the agent when this tool fits. It stops short of explicitly naming which sibling to use instead for token-level or global queries.

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