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

Annotations already declare readOnly=false, destructive=false, idempotent=true and openWorld=false, so the safety/mutation profile is covered elsewhere. The description adds the useful semantic consequence (timeline ranking), but says nothing about undoing via `unfavorite`, visibility of a favorite, or what the `note`/`private` flags change.

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?

A single front-loaded sentence that leads with the action and its effect. The parenthetical CLI-syntax example ('fav @handle a8r' / 'favorite @handle agentitter') is somewhat noisy but does illustrate the argument form.

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 3-parameter mutation tool with no output schema and zero schema coverage, the description leaves two of three parameters undefined and omits reversal/visibility behavior. Annotations cover the read/write profile, but the parameter-level gaps are significant.

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 0%, so the description must carry the burden, yet it only illustrates the `handle` argument via '@handle' and example syntax. The `note` (120-char) and `private` (default false) parameters are left completely unexplained 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?

Names a specific verb ('favorite') and resource (an author/@handle) and states the concrete effect: their posts rank higher in your timeline. That effect distinguishes it from most siblings, though it never explicitly contrasts with `ff`, `list_favorites`, or `unfavorite`, which would have made differentiation airtight.

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 stated purpose ('so their posts rank higher in your timeline') implies the use case for adding a favorite, but there is no when-not guidance and no pointer to the inverse tool `unfavorite` or to `list_favorites` for review. The agent must infer the full workflow.

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