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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds information the annotations do not: the return is plain text, not HTML or markdown, which matters because there is no output schema. It omits behavior on a missing/invalid slug, keeping it below 5.

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?

One sentence, zero filler, front-loaded with the verb and return format, ending with the prerequisite source of the slug. Nothing could be removed without losing meaning.

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 single-parameter read tool with no output schema, the description covers what it returns (plain text) and where the argument comes from. Only edge-case behavior (invalid or unknown slug) is unaddressed, a minor gap for this complexity.

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 100% with a single documented 'slug' parameter including a pattern. The description only adds provenance ('from list_blog_posts') and does not add format constraints beyond what the schema states. Baseline 3 applies when the schema carries the semantics.

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: 'Return the plain-text content of a HeroX blog article by slug.' The scope (HeroX blog articles) plus the slug lookup distinguishes it from list_blog_posts and implicitly from the docs siblings. It stops short of explicitly contrasting with read_doc, but the resource is narrow enough that selection is unambiguous.

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?

'by slug from list_blog_posts' tells the agent the prerequisite workflow: enumerate slugs with list_blog_posts, then read here. That is clear context for when to use it. It does not state exclusions (e.g. use read_doc for non-blog documents), so it falls short of a 5.

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