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

With no annotations, the description carries the full behavioral burden. It does disclose the credit cost of 1, which is genuinely useful, but says nothing about whether this is a pure generator or has side effects, what happens when optional fields like end or timezone are omitted, or how the result is returned. For a 6-parameter tool with zero annotation coverage, that is a substantial gap.

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 clauses, front-loaded with the purpose and followed by the cost note; there is no filler. It is arguably under-specified rather than verbose, which is a completeness problem rather than a conciseness one.

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 tool with 6 parameters, no annotations, no output schema, and non-trivial datetime/timezone semantics, the description is too thin. It never explains the return value, whether end is required in practice (schema marks nothing required despite "required" in the start/title descriptions), or how timezone affects the output.

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 description coverage is 100%, so every parameter is already documented in the schema with its type and format hints (ISO datetime, IANA). The description adds no further meaning, no defaults, no interaction notes between start/end/timezone. Baseline 3 is appropriate when the schema does the heavy lifting.

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?

The description states a specific verb and resource: "Build an .ics calendar event." An agent immediately knows this generates iCalendar data rather than performing a lookup or transformation. It does not need to distinguish itself from siblings (hash_text, qr_code, ssl_check, etc.), which are unrelated utilities, so the only gap is that it never says what the output is (presumably an .ics string).

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?

There is no when-to-use or when-not-to-use guidance, and no prerequisites or alternatives are named. The usage is strongly implied by the verb "Build," but the description does nothing to confirm the intended context (e.g., that this is for exporting a single event rather than a full calendar).

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