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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety and network profile is covered. The description adds only that the output contains a description and definition, which the output schema already carries, so it contributes little behavioral context (no auth, rate-limit, or failure behavior).

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 short sentences, front-loaded with the purpose, then input, then return shape. No filler or redundancy beyond the example restated from the 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?

For a single-param read-only lookup with an output schema, the description is nearly sufficient: purpose, input format, and return content are all covered without needing to explain return values. Only the absence of any routing guidance against search_lexicons keeps it from being fully complete.

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% and the single nsid parameter is fully documented in the schema, including the same app.bsky.feed.post example repeated in the description. Baseline 3 applies since the schema does the work and the description adds nothing new.

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 (resolve) and resource (lexicon schema / record type), clarifying that the NSID identifies a collection schema rather than a record. It is distinguishable from search_lexicons and get_record, though it never names those siblings explicitly.

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: the agent must infer it should call this when it has an NSID and wants to learn what the record type means. No when-to-use condition, prerequisites, or alternatives (e.g. search_lexicons) are stated.

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