read_diary

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered; the description goes beyond by warning that entries are overnight impressions, not verified facts, and by stating the return shape ({ data }, null when absent). The only shortfall is that the memory_id fallback chain (original messages vs. day diary vs. week diary) is described loosely enough to leave the exact resolution order slightly ambiguous.

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?

The usage trigger is front-loaded and each sentence carries information (scope, defaults, reliability caveat, alternate mode, return shape). The memory_id sentence is a long triple-branch clause that costs some readability, keeping it just below top marks.

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 no output schema, the description still discloses the return envelope and the null case, plus the reliability caveat an agent needs before quoting entries as fact. For a 4-parameter, all-optional read tool this covers everything needed to call it 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 baseline is 3, but the description adds real semantics the schema does not: omitting both date and week defaults to today plus yesterday, and memory_id switches the tool from diary retrieval to provenance lookup. The namespace parameter is left entirely to the schema, which is acceptable given its self-explanatory description.

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 diary") and immediately bounds the scope: a single day, a week, or the default today/yesterday. It distinguishes itself from siblings by naming recall as the tool for verifying details and explaining that memory_id redirects to provenance lookup rather than a day's entry.

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?

Explicit trigger is given ("when the person asks what happened on a certain day or during a stretch of time"), with multilingual cues. It also prescribes parameter selection: date for one day, week for a week, neither for today and yesterday, and memory_id as the alternate mode — that is when-to-use plus alternatives in one pass.

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