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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so "Read-only: returns public data and changes nothing" largely restates what the structured fields say. The credit cost ("Costs 1 credit per request") and the public-data-only scope are genuinely new behavioral facts the annotations do not carry. Missing is anything about failure modes for private/deleted posts or rate limiting.

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?

Three short sentences, zero filler, with the action and keying constraint front-loaded and the cost disclosure last. Nothing could be cut without losing information.

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 one-parameter read tool with full annotation coverage, the definition covers action, input key, safety profile, and cost. The one gap is that with no output schema, nothing tells the agent what a fetched post contains (author, text, metrics), leaving it to discover the return shape.

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 single parameter is fully documented at 100% schema coverage, including the accepted urn:li:activity:<id> form and post-link alternative. The description adds only the notion of being keyed by URN, which the schema already states in more detail, 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?

"Fetch a single LinkedIn post by URN" gives a specific verb (fetch), a specific resource (a single post), and a keying constraint (by URN). This implicitly separates it from linkedin_search_posts and the list-style siblings, but the description never names those alternatives, so the differentiation is left to inference.

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 "by URN" implies the tool is for when the caller already holds an activity URN or post link, which is useful selection context. However, there is no explicit statement of when to prefer this over linkedin_search_posts or linkedin_get_posts_from_profile, and no mention of what data is unavailable (e.g., comments, reactions) that would route the agent to linkedin_get_activity_comments or linkedin_get_post_reactions.

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