word-aligner

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

Annotations declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is already covered. The description adds substantial behavioral context beyond that: it explains tokenization rules (whitespace, tokenSplitChars, punctuation attachment), RTL indexing, vertical script orientation, and the adjacency constraint on alignments. It also discloses that tokens sharing a connection group get the same color automatically. This is rich behavioral detail that goes well beyond the annotations, though it doesn't explicitly state that the tool is non-mutating (but annotations already do).

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 description is long but densely packed with necessary operational detail. It is front-loaded with the core purpose and output, then proceeds logically through tokenization, RTL, vertical scripts, and alignment semantics. Every sentence earns its place; there is no fluff. However, it is quite lengthy and could arguably be trimmed in places (e.g., the vertical script paragraph is dense), but given the complexity of the tool, the length is justified. It loses one point for being at the upper limit of acceptable length.

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?

Given the tool's complexity (4 parameters, nested objects, 100% schema coverage, output schema present), the description is remarkably complete. It covers tokenization rules, RTL and vertical script handling, alignment constraints, and even provides examples. The output schema exists, so return values are covered. The only minor gap is that it doesn't explicitly state the maximum number of lines (8) or the alignment count limits, but those are in the schema. For an agent to call this tool correctly, everything essential is present.

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 the schema already documents every parameter. The description adds significant semantic value beyond the schema: it explains the tokenization algorithm in detail (how tokenSplitChars works, punctuation attachment, RTL indexing), the meaning of alignment tuples and the adjacency requirement, and the orientation semantics for vertical scripts. It also gives practical examples ('go.PST.IPFV' becomes three tokens). This goes well beyond the baseline 3 for full coverage, though it doesn't exhaustively map every setting (e.g., tokenMergeChar is only mentioned in the schema).

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 opens with a specific verb and resource ('Create a shareable Word Aligner diagram') and immediately clarifies the domain (word matching across stacked lines) and the output (URL plus preview image). It distinguishes itself from generic diagram tools by naming concrete use cases (translation alignment, interlinear gloss, RTL scripts, vertical scripts). No sibling tools exist, so differentiation is moot, but the purpose is unmistakable.

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?

The description gives explicit when-to-use guidance: 'Use this when the user wants to translate a phrase and show word correspondences, align a translation with its source... or build a Leipzig-style interlinear gloss.' It also provides detailed how-to instructions for tokenization, RTL handling, vertical scripts, and alignment tuple semantics. While it doesn't name alternatives (no siblings), it fully specifies the conditions for use and the operational rules, which is more than adequate.

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