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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description adds real value beyond them: it enumerates returned fields, notes that copied_at is conditional ('when the catalog recorded the day'), that license is 'when known', and warns that URLs carry utm_source=mcp/utm_medium=tool tracking parameters.

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?

Front-loaded with the core action in the first sentence, followed by a return-field list. Efficient overall, though the field enumeration plus the utm note makes the second half dense for a simple lookup tool.

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 responsibly describes what comes back, which covers the main completeness gap. It omits only edge behavior such as not-found handling, which is minor for a simple idempotent read.

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 0% for the single slug parameter, so the description must carry the semantic load. It does convey that slug is the identifier of exactly one entry, but adds no format guidance (case, hyphenation, or whether a name/ID is accepted) and does not explain failure when no entry matches.

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 plus the lookup key: 'Fetch one public catalog entry by slug.' The word 'one' plus 'by slug' implicitly distinguishes it from the list/search siblings, though none of them are named.

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: 'by slug' signals the precondition that you must already know the identifier, which in turn implies discovery flows belong to search_entries or list_new. No explicit when-to-use or when-not-to-use statement and no sibling is named.

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