Read your journal

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

readOnlyHint=true already tells the agent this is a safe read, so the description's job is lighter. It adds real value with the ordering guarantee ("oldest first") and the session-start framing, but leaves unclear what "most recent" defaults to and says nothing about pagination or entry contents.

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 short sentences, no waste, with scope and ordering front-loaded before the usage hint. Every clause earns its place.

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?

The tool is simple and read-only with no output schema, so the description is nearly sufficient. However, with no output schema the agent gets no hint of what a journal entry looks like, and the undocumented `limit` parameter leaves the return volume ambiguous.

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 only 50%: `since` documents its YYYY-MM-DD format, but `limit` has no description or default anywhere. The description could have explained how many entries are returned by default and how limit interacts with the oldest-first ordering, but it does not.

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 ("Read your ... journal entries") plus scope and ordering ("most recent", "oldest first"), which no sibling claims. It doesn't explicitly separate itself from memory_read or memory_search, so an agent must infer the journal-vs-memory distinction from the name alone.

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?

Gives a concrete trigger: "Use at the start of a session to pick up where you left off." That is a clear when-to-use signal, but there is no when-not guidance and no pointer to journal_append or memory_search as alternatives.

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