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 bar is lower. The description still adds valuable behavior beyond them: per-page billing at $0.003, a 12-notes-per-page cap, and the returned fields including engagement and quoted posts. This is meaningful cost and shape disclosure.

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 action, followed by return shape, sort/page behavior, and cost. Every sentence carries distinct information with no filler.

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?

With no output schema, the description compensates by enumerating returned fields, sort ordering, page size, and billing. Combined with annotations covering the safety profile and full schema coverage, an agent has everything needed to invoke 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 coverage is 100%, so the baseline is 3. The description adds marginal meaning by restating the sort semantics ('newest first or top first') and the page size/billing unit ('Up to 12 notes per page'), reinforcing rather than duplicating 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?

The description uses a specific verb ('Search') and a clearly bounded resource ('Substack Notes'), distinguishing it from siblings like search_substack (posts), search_substack_users, and substack_note_details. An agent can identify the target entity without opening the 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?

Usage is implied by 'Search Substack Notes by keyword' and the sort options, but there is no explicit when-to-use/when-not guidance and no routing to alternatives such as substack_note_details or substack_user_activity. The agent must infer the appropriate case.

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