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

Annotations already cover safety and idempotency (readOnly=false, destructive=false, idempotent=false, openWorld=false); the description adds genuinely new behavior: per-item outcome vocabulary (added/already_present/unresolved) and that the call is free. It does not explain what triggers 'unresolved' or whether partially-added batches roll back, which keeps it at 4 rather than 5.

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 sentences, ~20 words, with the action and accepted input forms front-loaded and the return shape plus cost trailing. Nothing is wasted and nothing needs to be re-read.

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 correctly steps in to summarize the per-item return values, which is the key thing an agent needs. It omits batch limits (200 max, in schema) and failure/remediation guidance for 'unresolved' items, so it is strong but not fully 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 description coverage is 100%, so the schema already documents both 'id' and 'companies' fully. The description's identifier list ('domain, name, LinkedIn URL, or id') restates the schema's own wording rather than adding format or precedence rules, so it earns the baseline 3.

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+resource ('Add companies ... to a watchlist') and enumerates the accepted identifier forms, so the agent knows exactly what the tool does. It never names the inverse (remove_from_watchlist) or the prerequisite (create_watchlist / list_watchlists) from its sibling set, which keeps it short of a 5.

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?

Usage is only implied: the required 'id' parameter signals that a watchlist must already exist, but the description never says so, nor does it point to create_watchlist/list_watchlists for obtaining one. No when-not-to-use or alternative routing is provided.

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