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

Annotations already cover the safety profile (readOnly, non-destructive, open world), so the extra value here is the cost disclosure ("Billed $0.003 per page") and the enumeration of returned fields, which matters since no output schema exists. It stops short of disclosing pagination limits or behavior for invalid publication handles.

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, front-loaded with the capability, then the return fields and price. Nothing is redundant for an agent deciding whether to call it.

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 what the tool does, what comes back, and what it costs, with annotations handling safety and the schema handling all six parameters. Only gap is that podcasts_only and get_sentiment aren't hinted at in the description, but the schema documents both fully.

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% and every parameter already has a description, including billing per page and the sentiment surcharge. The description's only additions are restating the sort modes and return fields, which the schema largely covers, 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?

States a specific verb and resource ("Get a publication's posts") and enumerates the three modes: newest first, top, most discussed, plus keyword search. That scope word "publication's" separates it from cross-publication siblings like search_substack, though no sibling is named explicitly.

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 sort enum and keyword search are explained, so an agent knows the modes available. But there is no guidance on when to prefer this over substack_user_posts, substack_publication_details, or search_substack, and no stated prerequisites such as whether the publication must exist.

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