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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile requires no description support. The description does add return-field disclosure (id, title, url, text), valuable since there is no output schema, but the parenthetical "(what getDetails returns)" is ambiguous about whether fetch duplicates getDetails output or just its text field.

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 compact sentence plus a routing clause — no padding, and the return shape is front-loaded. The trailing parenthetical is cryptic enough that it slightly undercuts the otherwise tight structure.

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 simple one-required-param read with no output schema, the description covers the return payload and points to getDetails. The key unresolved question — why fetch exists when getDetails exists, and whether their outputs overlap — is exactly what an agent needs to choose correctly, and it is not answered.

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 id (UUID or jam.dev URL) and the intent/llm_model telemetry params are already fully documented. The description adds no syntax or format meaning beyond the schema, so the baseline 3 applies.

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?

"A Jam as a citable document: id, title, url and text" states the resource and exactly what comes back, which makes it distinguishable from the raw-detail siblings. It falls short of 5 because it is a noun phrase rather than a verb+resource statement, so the action (retrieve) is only inferable from the tool name "fetch".

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 getDetails to investigate" names the alternative, which is real routing guidance. However, the selecting condition is left implicit — the agent must guess that fetch is for citation/summary and getDetails for deeper inspection, and there is no guidance on when neither applies.

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