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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows it is a safe read operation. The description adds substantial behavioral context beyond that: it is public and requires no auth, it returns a specific arithmetic breakdown, it explains the RULE ZERO condition and the COPIED check (and that the copied check is a proven duplicate check, not a model judgement). This goes well beyond the annotations to describe exactly what the tool does internally and what guarantees apply.

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 long but well-organized: it leads with the core purpose, then explains the input, then enumerates the return components, and finishes with auth. Every sentence contributes value, but it is dense and could overwhelm an agent scanning quickly. It is front-loaded and structured effectively; it just misses a perfect 5 because it is verbose relative to the simple single-parameter tool.

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?

Given the complexity of the scoring system and the absence of an output schema, the description thoroughly explains what the tool returns: the engagement weights (replies x13.5, bookmarks x10, etc.), the units, the views dampening, RULE ZERO, the COPIED check with link, and all boosts. It also covers the public/no-auth availability. Nothing essential for understanding the output or calling the tool correctly 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?

The schema only provides the parameter name and type (string) with 0% coverage of descriptions. The description fully compensates by explaining that post_id is 'the numeric id from any x.com/…/status/<id> link', giving the agent clear guidance on how to obtain and format the parameter. This is precise, actionable, and covers the parameter semantics completely.

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 is explicit about what the tool does: it provides a detailed breakdown of why a post received a particular score. It clearly names the verb ('explain') and resource (a single post's score breakdown), and the detail about engagement weights and special rules distinguishes it from any vague or generic explanation. This is far beyond a tautology and clearly separates it from siblings like boosts_explain or justify_seeds.

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 description clearly states the input requirement (post_id) and the purpose, which implicitly communicates when to use it: whenever you need to understand the scoring of a specific post. It does not explicitly name alternative tools or exclusion conditions, but the highly specific scope (one post, scoring breakdown) makes usage context clear. Missing explicit contrast with siblings prevents a 5.

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