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

Beyond the annotations' readOnly/idempotent declarations, it discloses error semantics ('an unknown or unapproved slug is an error, not an empty result') and health-probe freshness cadence (hourly for priority, rolling daily otherwise), which the agent cannot infer from 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?

Front-loaded with the core action and precondition, and most sentences carry distinct information. Slightly dense as one block, and 'it takes no filters and no paging' partially restates the single required-slug schema.

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?

An output schema exists, yet the description still summarizes the returned fields and freshness caveat, and it covers the error path and slug provenance. Nothing needed to invoke it correctly is missing.

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%, so the baseline is 3; the description adds provenance guidance by telling the agent where a valid slug comes from ('from a previous discover_capabilities, search_registry or list_entries result') and reinforces the no-guessing rule, though it adds no format detail beyond the schema.

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 ('Fetches the full record of ONE approved registry entry') plus the precondition (exact slug already in hand), which cleanly separates it from the listing/search siblings named in the same sentence.

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?

Explicitly names alternatives and the condition that selects each: search_registry for keywords, discover_capabilities for plain-language needs, list_entries for the whole catalogue, and an explicit prohibition on guessing a slug. Routing is unambiguous.

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