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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description still adds real behavioral context the annotations cannot: the isTyomarkkinatori:true flag, the mandatory `dataSource` attribution per Job Market Finland terms, and the locale fallback when a listing is missing in the requested language. It stops short of noting what happens for an unknown id or an unreachable source, which keeps it at 4.

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, front-loaded with purpose, then usage, then the compliance caveat. The mid-sentence enumeration of returned fields is slightly padded, but the ordering is sensible and no sentence is redundant with 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?

With an output schema present, the description need not explain return values, yet it flags the one return detail with legal consequences (the required dataSource attribution) and the locale fallback behavior. Combined with the annotations, an agent has everything needed to call this correctly.

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, and the schema already documents jobId's format and locale's enum/default. The description adds cross-tool meaning by telling the agent that jobId comes from the `id` field of a search_jobs result, which is genuine value beyond the schema text.

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 ('Fetch the complete details for a single JobCrawls listing by its id') and enumerates the returned payload. It also positions itself relative to the sibling search_jobs, so an agent can distinguish this retrieval call from the search call without opening either schema.

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 the trigger condition ('Useful after search_jobs when a user wants to know more about a specific opening') and the alternative it follows from, plus the data dependency ('takes the `id` field from a search_jobs result'). Nothing about when to reach for this tool is left to inference.

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