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

Annotations only say non-read-only, idempotent, non-destructive; the description goes further by disclosing PATCH-style merge semantics ("only the fields you pass change"), that target accounts are immutable here, and the time-based eligibility cutoff. That is exactly the extra context the annotations do not provide.

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?

Four tight sentences, front-loaded with the core operation and identity, then merge semantics, then editability boundaries. No filler and no restatement of the title or name.

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?

Covers eligibility, partial-update behavior, and the account-immutability boundary, which is everything needed to invoke a 10-param mutation safely. It does not say what a successful edit returns, which is a minor gap given there is no output schema.

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 60%, and the description maps the editable parameter groups (text, media, first comment, scheduled time, per-platform settings blocks) so the agent knows which top-level params are updatable. It still defers per-field rules (pinterest board_id requirement, TikTok privacy sourcing, tag limits) to the schema.

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 (edit a scheduled post) and pins the identity semantics with "keeping the same post (uid from list_posts)". It is clearly distinguishable from create_post and cancel_post, which it names.

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?

Gives explicit when-to-use (only posts still scheduled, not already publishing or due within minutes) and explicit when-not/alternatives (change target accounts via cancel_post and create_post instead). Nothing is left to inference.

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