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

Annotations already cover the safety profile (readOnlyHint=true, openWorldHint=true, destructiveHint=false), so the description's main added value is the billing rate of $0.003 per request, which is genuinely useful operational context. It also enumerates the returned fields, compensating for the absence of an output schema. Pagination caps are left to the schema.

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 sentences, all front-loaded: purpose first, then return shape, then cost. No filler or repetition. Slightly padded by the long field enumeration, but each element carries information.

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 read-only two-parameter search with no output schema, the description supplies the return-field list and pricing that the structured fields cannot. The remaining gap is routing guidance against the many sibling Substack search tools, which is the one thing an agent still has to guess.

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% – both the 500-character query limit and the 1-4 page range with 20 profiles per page are documented in the schema itself. The description adds nothing about parameter syntax or format beyond what the schema provides, 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?

The description states a specific verb ('Search') and resource ('Substack authors and publication profiles'), and names the match key (name or keyword). It enumerates the returned fields, which lets an agent distinguish it from generic search tools. However, the phrase 'publication profiles' blurs the boundary with the sibling search_substack_publications, and no sibling is explicitly excluded.

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?

No when-to-use or when-not-to-use guidance is given, and no alternative sibling (e.g. search_substack, search_substack_notes, search_substack_publications) is named. The agent must infer the appropriate context from the tool name alone.

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