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

Annotations already declare readOnly, non-destructive, closed-world, so the safety bar is low. The description still adds real behavioral context: results are newest-first, custom-target restrictions apply, and pagination uses nextOffset rather than the opaque history tokens used elsewhere. It stops short of describing rate limits or result-shape behavior, but that is largely covered by the output 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 tight sentences with the core action front-loaded, then pagination guidance, then sibling routing. Every sentence earns place, though the final clause 'the search tool finds streams, not posts' is slightly compression-heavy and takes a re-read to parse.

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 an output schema present, return values need not be described, and the description covers ordering, scoping, access restrictions, and pagination semantics. It is close to complete; only edge behavior (empty results, escaping in text queries) is left implicit.

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 streamId, text syntax, limit, offset, and the ISO date bounds. The description reinforces ISO date bounds and the nextOffset contract but adds little syntax or format meaning beyond the schema, so the baseline 3 is correct.

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 with scope: 'Search full post text within one accessible stream, newest first.' It explicitly distinguishes itself from get_stream_posts and from the stream-level 'search' sibling, so an agent can route correctly without opening either 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?

Names the alternative ('Use get_stream_posts to page by date without a text query') and gives the selecting condition (text query vs. date paging). It also carves out the boundary that the search tool finds streams, not posts, which is exactly the disambiguation an agent needs.

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