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

The annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, covering the safety profile. The description adds no behavioral detail beyond the obvious read semantics—nothing about pagination, ordering, or side effects—so it adds value mainly by restating the domain 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?

The description is two short sentences with no fluff. The first sentence states the operation directly, and the second adds a concise user-oriented rationale without repeating the tool name or schema details.

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 read-only listing tool with full parameter descriptions and safety annotations, the description covers the essential context. It lacks details about return shape or ordering, but those are not critical for a tool this straightforward and no output schema exists to clarify them.

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 both parameters have useful descriptions in the schema: limit includes default/max, and subreddit clarifies the format. The tool description itself adds no parameter-level meaning, 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?

The description states a clear verb and resource: "Get saved posts that haven't been read yet." The qualifier "saved" and "haven't been read yet" differentiates it from a generic recent-posts or search tool, though it does not explicitly name a sibling as an alternative.

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?

The phrase "Useful for finding posts the user saved but hasn't gotten to" gives clear user-facing context for when the tool is appropriate. It does not explicitly state when not to use it or name an alternative, so it stops short of full exclusion guidance.

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