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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds that exactly one item is returned and that matching is exact on three key types, but says nothing about what happens when no item matches.

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?

One sentence, no filler, and the lookup keys are front-loaded immediately after the verb and resource. Nothing could be trimmed without losing information.

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 one-parameter read-only lookup with full annotations and an output schema, the description covers the essentials: what is fetched and how it is keyed. The only real gap is not-found behavior and routing versus search_records, which are secondary given the surrounding structured data.

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 100% and the single parameter's description ('Record id, slug, or exact title') already enumerates the accepted forms, so the description largely restates the schema. Baseline 3 applies when the schema carries the parameter semantics.

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?

Specific verb ('look up') plus resource ('one directory item') and the three accepted lookup keys. It does not distinguish itself from siblings like search_records or list_sections, and the title ('Get an MCP server') is narrower than the description's 'directory item', leaving a small ambiguity about what a record actually is.

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 phrase 'by id, slug, or exact name' implies this is an exact-match single-item lookup, which implicitly contrasts with the fuzzy retrieval implied by search_records. However, it never states when to use this instead of search_records or how to obtain a valid id in the first place.

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