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

Annotations already declare readOnly, idempotent, non-destructive behavior. The description adds that threads are public, that the response includes the current UTC eligible date, and that category=yesterday pairs with optional news_date. This is useful context beyond annotations, though auth/rate-limit behavior is absent.

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 tightly written sentences, front-loaded with the core action and then the special-case instruction. No filler or redundant restatement.

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 5-parameter feed with pagination (cursor), ordering (order), and limit controls, the description is incomplete. It omits pagination and result-shaping guidance, and with no output schema and 0% schema coverage it should do more.

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 0%, so the description must carry parameter meaning. It explains category and news_date for the Yesterday case but says nothing about limit, order, or cursor, leaving three parameters undocumented in both schema and description.

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 (Read) and resource (public SNAIL threads), so an agent knows it is a feed/list operation. It does not explicitly differentiate from siblings like snail_thread, but the plural 'threads' implies listing.

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?

Provides a conditional instruction for the Yesterday category but does not say when to choose snail_feed over snail_thread or other siblings. No when-not guidance or alternative routing is given.

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