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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=true, and openWorldHint=true, so safety and idempotency are covered structurally. The description adds genuinely useful behavioral scope: the requirement that at least one mutable field be supplied and the fact that published posts are out of reach. It does not restate the idempotency semantics, which the schema documents, but the added constraints make it more than a repeat of annotations.

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 tightly written sentences with the core action front-loaded and constraints following. There is mild redundancy between the first parenthetical (post_urn returned by list_scheduled_posts) and the closing clause, but nothing that undermines the structure.

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?

An output schema exists, so return values need not be explained. The description covers the mutation scope, required inputs, key parameter provenance, and the restriction on published posts, which is everything an agent needs to invoke it correctly.

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 100%, so the 3 baseline applies, but the description adds a real cross-parameter constraint absent from the schema: only account_id and post_urn are marked required, yet the description correctly states that at least one of text or scheduled_at must be provided. That goes beyond the per-field descriptions.

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 (update an existing scheduled LinkedIn post) and scopes it to text and/or scheduled time. It is clearly distinguishable from siblings like create_post, delete_scheduled_post, and list_scheduled_posts without opening any schema.

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?

Explicitly states the precondition (at least one of text or scheduled_at must be provided), the source of the key parameter (post_urn from list_scheduled_posts), and an exclusion (published posts cannot be edited through Reach). All the when-to-use and when-not-to-use context is present.

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