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

The annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description still adds real behavioral value beyond them: result ordering (newest first) and, critically, the hidden default that 'older off-focus posts are excluded unless include_archived is true' — a non-obvious filtering behavior an agent would otherwise miss.

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. The primary behavior (list, newest first) leads, and the exception (archived exclusion) follows immediately.

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 read-only five-parameter list tool with no output schema, the description covers ordering, available filters, and the non-default archived behavior — the things an agent cannot infer from the schema alone. Pagination defaults are visible in the schema, so nothing essential 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?

Schema coverage is only 40%, so the description must compensate, and it does for the most opaque parameter: include_archived gets meaning ('includes older off-focus posts') that its bare default=false schema entry does not convey. tag and year are already documented in the schema and are restated here. limit and offset remain unaddressed in prose, though their defaults and ranges are self-explanatory in the schema.

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 and resource plus sort order: 'List essays, newest first, optionally filtered by tag or year.' That distinguishes it from get_post (single item) by implication, but it never names search or explains how it differs from a free-text query, so sibling differentiation is incomplete.

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?

Usage is implied rather than stated: you infer this is the browse/enumerate path and get_post is the single-item path. There is no explicit 'use this instead of search when...' guidance and no prerequisites, so the agent must guess when browsing beats searching.

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