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

With no annotations, the description carries the full burden. It discloses the return behavior (exactly which slugs were added/changed/removed, or current version and library counts) and instructs the caller to record the version. It implies a read-only operation (no mutation mentioned), which is reasonable for a 'check' tool. However, it doesn't state side effects or error handling explicitly, so it's not a perfect 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?

The description is front-loaded with a clear purpose and then explains usage and behavior. It's somewhat long (four sentences) but each sentence adds value—e.g., the reasoning about re-pulling only changed patterns is useful. There is no fluff, though it could be slightly condensed without losing clarity.

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?

Given there is no output schema, the description explains return values well: it lists the types of changes reported and mentions that 'library counts' are included with no arguments. It also tells the caller to record the version for future use, which is important for the tool's workflow. It doesn't describe exact response formatting or error cases, but for a simple read-only tool the completeness is adequate.

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?

The schema covers the single parameter 'since' with a clear description, and the tool description adds extra context: where to source the version ('from `version` in a previous check_updates or /p/manifest.json') and the effect of omitting it. This goes beyond the schema's baseline, enriching the parameter's meaning.

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 verb and resource: 'Check whether patterns you already built with have changed.' It clearly distinguishes itself from sibling tools like list_patterns and get_pattern by focusing on detecting changes (added, changed, removed) rather than listing or fetching. The purpose is unmistakable.

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 usage context: pass the version you built against to get a delta, or call with no arguments to read the current version and library counts. It implies a 'when to use' scenario (before re-pulling patterns) and contrasts with re-pulling all patterns, but it doesn't name alternative tools explicitly or state when not to use it. Strong but not exhaustive.

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