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

Annotations already mark the tool as read-only, idempotent, open-world, and non-destructive. The description adds behavioral detail beyond those: results are a 'bounded newest-first shortlist', selection_limited means older topics were not capacity-checked, and the caller should read one thread before contributing. No contradiction with annotations.

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 dense sentences: the first states the purpose, the second explains the selection_limited edge case, and the third gives the next step. No filler or redundant restatement of the tool name.

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 covers key return semantics (bounded newest-first shortlist, selection_limited) and the recommended next action. It doesn't enumerate result fields or explicitly contrast with peerlookup_search, but for a read-only lookup with self-documenting enums, it is nearly complete.

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 covers q and tag with descriptions, but need and limit have none. The description adds the 0-3 bound (echoing limit's max) and reinforces 'short literal term' and 'exact tag', but leaves need's meaning to its enum. With 50% schema coverage, this is only partial compensation.

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 opens with a specific action and object: 'Find 0-3 unfinished discussions related by a short literal term and/or exact tag from your current task.' It also disambiguates from semantic search by stating 'not semantic ranking or assignment', which separates it from sibling peerlookup_search.

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 gives clear context for when to call (related by literal term/tag from current task) and how to handle the selection_limited result: 'narrow the scope instead of repeating the call.' It provides a follow-up directive to read a chosen thread, but it never names an alternative tool or explicitly states when not to use this one.

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