Lulu Registry MCP

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

Annotations already declare readOnlyHint=true, covering the safety profile. The description adds value by enumerating exactly what the read returns: install commands, transports, categories, registry links, and trust score. This makes the behavioral scope concrete beyond the annotation, though it omits error cases or pagination—minor given the read-only nature.

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 with the purpose and content list front-loaded, followed by usage guidance. The enumeration of return fields is long but each item is relevant and helps the agent understand the tool's scope without bloat.

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 a single well-explained parameter, a readOnly annotation, and an output schema already present, the description covers purpose, usage, parameter source, and return contents. Nothing critical is missing for correct invocation.

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 0%, so the description must carry the parameter meaning. It does so by specifying the slug is 'as returned by search_mcps', giving it a clear provenance and role as a lookup key. This is more than the bare 'string' type provides, though it doesn't describe format constraints or validation rules.

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 'Full details for one MCP server from the unified index, by slug', which names a specific resource and retrieval verb. It explicitly differentiates from the sibling search_mcps by stating the slug comes from that search, so an agent can distinguish without opening schemas.

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 description explicitly states 'Use after search_mcps when the user wants to install or inspect a specific server.' This gives both a clear trigger condition and a positional relationship to the only sibling tool, making the selection decision unambiguous.

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

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

With readOnlyHint=true already covering the safety profile, the description adds valuable behavioral context: cross-registry aggregation, deduplication, ranking by a trust score, and the return shape (ranked servers with install one-liners and links). It also discloses how category and limit alter behavior. It stops short of noting pagination or rate-limit behavior, but for a read-only search tool the bar is already largely met.

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?

Three sentences, each with a distinct job: scope and behavior, when-to-use with examples, and return format plus parameter semantics. The most important information is front-loaded in the opening sentence, and there is no filler or redundancy.

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?

For a read-only search tool with an output schema, the description covers purpose, usage, return format, and parameter behavior—most of what an agent needs to call it correctly. The output schema handles return-value detail and annotations handle safety. The only real gap is a lack of explicit differentiation from the get_mcp sibling, since the description implies but never states the search-vs-retrieve split.

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 0%, so the description must compensate—and it does. It explains that category narrows results with concrete examples ('security', 'data') and that limit caps results with a 1-10 range and default 8. The query parameter's semantics are conveyed implicitly via the example queries rather than defined explicitly, which is the only gap.

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 states a specific verb and resource ('Search every major MCP registry at once') and enumerates exactly which registries are covered (official, Glama, PulseMCP, Smithery). Concrete example queries ('find me a weather MCP') make the capability unmistakable, and the emphasized 'FIND an MCP server' clearly separates it from the get_mcp sibling's retrieval role.

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?

'Use whenever you need to FIND an MCP server for a capability' is explicit when-to-use guidance, backed by three realistic query examples. However, it never names get_mcp as the alternative for known-server lookups, so there is no explicit when-not-to-use or exclusion guidance.

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