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

Annotations already carry the safety profile (destructiveHint=true, readOnlyHint=false, idempotentHint=false), so no contradiction exists. The description adds genuine behavioral context beyond annotations: client-provided media references are imported in the same action, and the response surfaces mutation result, platform readiness, blockers, and follow-up data. It does not spell out overwrite semantics for existing media/schedules, but that burden is largely covered by the destructive hint.

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?

Two sentences with no filler, and the core action is front-loaded before the media-import and return-value details. The first sentence's list is dense but earns its place given 28 parameters and nested objects. It is efficient and well-ordered, though slightly heavy relative to the leanest possible phrasing.

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 28-parameter tool with nested objects, an output schema, and annotations, the description covers the action scope, same-action media import behavior, and what the response reports. It omits explicit sibling-routing guidance, but the rich schema (82% coverage) and its own pointer to postly_get_channel_schema fill most remaining gaps.

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 82%, so the schema already documents the parameters in detail; the description adds only a high-level grouping (content, media, labels, targets, schedules) and notes that media references are imported in the same action. That maps to media_file/media_uploads fields but offers no per-parameter syntax beyond what the schema provides, so baseline 3 is appropriate.

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 uses a specific verb ('Updates') and resource ('existing Postly post'), then enumerates the editable dimensions: content, media, labels, social or email/newsletter targets, and schedules. This clearly distinguishes it from siblings like postly_create_post (new post), postly_delete_post (removal), and the read-only get/list tools. The same-action media import and return-value scope further sharpen the tool's identity.

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?

Usage is implied — use this when modifying an existing Postly post — but the description never names alternatives or states when to prefer this over postly_create_post, postly_delete_post, or postly_upload_media. There are no explicit when/when-not conditions or exclusions, so the agent must infer routing from the siblings and schema references to postly_get_channel_schema.

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