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

Annotations already declare readOnlyHint and openWorldHint=false, so the safety profile is covered; the description adds genuinely new behavior: case- and accent-insensitive matching, a fixed 30-result page, and newest-first ordering. It omits any note on result fields or limits beyond pagination, but the added behavioral detail is well above the annotation baseline.

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 dense sentences with no filler: scope first, then pagination mechanics. Every clause carries usable 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 three-parameter read-only search with no output schema, the description covers matching semantics, ordering, page size, and the pagination loop, which is everything an agent needs to call it and page through results 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 would be 3, but the description adds meaning beyond the schema by clarifying that q matches ALL words (AND semantics) rather than any, and that before should be taken from the last result's message id. That is practical invocation guidance the schema does not state.

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 ("Searches every channel") plus the matching scope ("all the words of q, ignoring case and accents"), which separates it from list_channels and get_channel 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?

Clear operating context: search spans all channels unless site_id narrows it, and continuation requires passing the last result's message id as before. It does not explicitly name when to prefer list_channels or get_channel instead, so it stops short of full when/when-not routing.

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