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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuinely new behavioral information: unknown slugs are surfaced in a "missing" field rather than silently resolved, which tells the agent how partial failures behave.

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 short sentences with zero filler; the cardinality constraint is front-loaded and the edge-case behavior follows. Nothing redundant with the schema or annotations.

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 must carry return-value context, and it does partially by naming the missing field for unresolved slugs. It doesn't say what a successful comparison result actually contains (what fields are compared), leaving a minor gap for a tool with no output schema.

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% and the minItems/maxItems bounds (2-5) are already enforced structurally, so the baseline is 3. The description adds semantic value by explaining what happens to invalid slug values (reported in missing, not guessed), which the schema does not express.

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 ("Compare") and resource ("published tools") plus an explicit cardinality scope ("two to five"). The multi-tool scope cleanly separates it from the singular get_tool sibling without needing to name it.

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?

The "two to five published tools side by side" phrasing implies when this is appropriate (multi-tool comparison rather than single-tool lookup), but no sibling is named and no explicit when-not guidance is given. Usage is inferable rather than stated.

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