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

With no annotations, the description carries the burden and does disclose real behavior: the exclusion of followed channels, the billing rate (1 credit per call), and the fields returned per channel. It omits pagination/rate-limit behavior, but the safety and cost profile is otherwise covered by the description itself.

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?

One dense paragraph, front-loaded with the core search behavior, followed by output fields, exclusions and billing. Every sentence carries information; nothing is padding.

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 and no annotations, the description goes out of its way to enumerate the returned fields (followers, verification, description, invite code) and the billing cost, which is exactly what is missing from structured data. Minor gaps remain around pagination and result ordering.

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 100%, so the schema already documents view, limit, query and country. The description reinforces the query-vs-view relationship ('without a query the directory's recommended...') but adds no format or range detail beyond the schema, so the baseline of 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?

It names a specific verb and resource ('channel directory: channels whose name matches query...') and spells out the two operating modes (query-driven vs. view-driven). It also distinguishes itself from siblings by explaining that the returned invite code is meant to be used with Get Channel / Get Channel Posts.

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?

It clearly states the query/no-query branches and notes that followed channels are excluded, which tells the agent when results will be incomplete. It points at the follow-up siblings to use with the invite code, but does not explicitly say when to prefer this over a direct channel lookup.

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